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Memory vs. Storage ~Both Are Units to Store Data, but _ _ _ Is Different!~

What is the difference between memory and storage?

Hi everyone, I'm Yoshi.

In this article, I'm going to explain the differences and characteristics of "Memory" and "Storage", which are typical hardware components.

We will explore the points below:

  • What's the difference between 8GB of memory and 256GB of storage?
  • What is volatility?
  • Why does more memory make a computer faster?

Let's get started!

Mistakes in the Newspaper

mistake in newspaper

Shown above is a comparison table of the specs between Play Station 4 and Wii U game consoles which was taken from one of the Japanese newspapers. In fact, it became a hot topic on social media because there was a mistake in this table.

So, can you see what is wrong in this table?

storage capacity is listed as memory capacity

It is "32 gigabytes / 8 gigabytes", which is listed in the memory row of the Wii U column. This is because the storage capacity was listed as the memory capacity.

"Memory" and "storage" are two different types of hardware. Nevertheless, it has been regarded as if they were the same. So, why did the newspaper, an influential medium, contain wrong information? I guess this is because memory and storage are both devices to store data, and their functions are similar.

However, even though they are the same device in terms of storing data, their uses are completely different. I will clarify the difference between memory and storage.

What Is Memory and Storage?

What Is Storage?

concept image of storage

"Storage" is a general term for a device that permanently stores data. For example, it is used to store photos, music, and the installed applications.

This is rather easy to imagine, isn't it? Because when you buy a product such as a smartphone or a computer, you must have chosen how much storage space you wanted to use.

storage capacity in iPhone12

For example, if you look at the product page of the iPhone 12, you will see a section that describes the capacity. This is the part that shows the storage capacity on this model. We can see that there are three different storage capacities available: 64GB, 128GB, and 256GB.

The larger the storage capacity, the more data you can store. So, the 256GB storage is the best for storing a lot of photos and music data. Of course, the price will be higher.

Storage Types

types of storage

Hardware that is actually used for storage can be found in the following:

  • HDD:Hard Disk Drive
  • SSD:Solid State Drive
  • SD card

HDD components

A "HDD: hard disk drive" is device that can write data to a disk using its "head" to a "platter" that records magnetic information.

Since the disk must be rotated and the head is moved to read and write data, the reading/writing speed of HDDs is slower than that of SSDs (to be mentioned below).

Also, if the disk and head hit each other, the disk gets damaged and data could be lost. For this reason, they are not often used in products such as smartphones and laptops that are likely to be shocked when carried around.


"SSD: Solid State Drive", on the other hand, uses integrated circuit assemblies to store data. Since there are no physical moving parts like the heads of HDDs, the writing speed is faster and the shock resistance is more superior compared to HDDs. They are also smaller in size and more power-efficient than HDDs, so they are widely used in smartphones and laptop computers these days. Because of this, their price is more expensive than the HDDs.

SD Card

HDDs and SSDs are built into smartphones and laptops and are basically not removable, but there are also storage devices that can be removed and transported, such as "SD cards".


There is also "cloud storage," where data is stored in a storage provided beyond the Internet, such as Google Drive and iCloud.

Cloud storage is very easy to use because the data stored on your smartphone is synced to other devices such as laptops via the Internet. Since there is no need to manage physical storage, it also reduces the risk of data loss.

What Is Volatile and Non-volatile?

Memory and storage have some characteristics that are important to understand the difference between them. They are "volatile" and "non-volatile".

what is volatility?

The word "volatile" generally refers to the evaporation of a liquid into a gas. In the IT world, it refers to the evaporation of data, i.e., the disappearance of data.

The opposite, "non-volatile", means that the data will not be lost. This means that even if you turn off your computer or phone, the data will continue to be stored without disappearing.

Storage is capable of storing data permanently, thus storage is a non-volatile storage device. After listening to this, you may be thinking, "Oh, that's so obvious". Because if your photo data is lost just by turning off your phone, then it's about as useful as a chocolate teapot.

The reason why I emphasized this point is because there are some devices that are volatile, that is, data is lost when turning off the phone. This is memory, which I will explain next.

What Is Memory?

Concept image of memory

"Memory" is a device that temporarily stores data. Unlike storage, when you turn off your computer or smartphone, the stored data will vanish. In other words, memory is a volatile storage device.

what kind of data is stored temporarily?

You may be wondering, "what kind of data can be stored temporarily and does not need to be stored permanently?". So, let's think about temporary memory with an example.

When Is Memory Used?

Example of Memory Usage Part 1

Think about the scene when you do research on the Internet.

scene of browsing

On the search page, you can enter the term you want to look up, and from the list of candidates displayed, you can click on the link to the page you want to view. However, if the content of the page is not what you are looking for, you may want to go back to the search results page and open the next candidate page.

In order to make this seemingly simple operation happen, the browser, which is an Internet browsing application, needs to remember the path of every page opened by the user.

The same is true when multiple tabs are opened for searching. The reason why you can jump to another tab and back again is because the app remembers the information of all the tabs.

browsing path is stored in memory

However, it is unlikely to be necessary to keep this information permanently. Therefore, the path followed by the user can be stored in memory.

By the way, if you like a page you have viewed, you may want to bookmark it. So, where should this bookmark information be stored in storage or memory? Since you are storing the URL so that you can visit the page again in the future, the bookmark needs to be stored permanently. Therefore, this information is stored in storage, not in memory.

Example of Memory Usage Part 2

As another example, let's consider the case of creating a document in a text editor.

scene of typing

You are typing and entering text. But you still want to change the text, so you delete it with the delete key. Then, you start writing a new text, but you think the previous one is better, so you restore the original text by "Undo" operation. With handwriting, the act of "erasing a document" itself cannot be undone, but with a computer, it can be easily undone. Why is that?

typing log is stored in memory

This is because the text editor software remembers the log of operations such as entering and deleting text. As you may have guessed, this information is stored in memory. This is because there is no need to keep that log permanently.

On the other hand, documents created there can be saved in the computer by using the "Save" operation, which needs to be stored permanently, so it is stored in storage.

So far, I hope you have understood how memory and storage are used in different ways. These are just a few examples. There is a lot of other information stored in the memory that is necessary to run the software.


This is off topic, if you are a programmer, you need to understand this concept of memory. Because a design that uses memory efficiently is required for a program to run comfortably.

Memory and Storage in IT Products

From here, let's look a bit at the memory and storage in IT products.

Wii U

Wii U specification

First, let's talk about Wii U, which I explained at the beginning of this article. According to Nintendo's official website, Wii U comes with 8GB or 32GB of storage capacity. The memory capacity has not been disclosed.

Game save data is not stored in memory, but in storage, because it must be left permanently even when the console is turned off. This means that there is 8GB or 32GB of space to store this saved data.

storage capacity is listed as memory capacity

Regarding Wii U story I mentioned, the error in the newspaper was that "the storage capacity used to store the saved data was listed as the memory capacity. Now you can understand the difference.


This storage seems to be used for storing data other than saved data. So, technically, not all of the 8GB or 32GB space can be used for storing saved data.


Next, let's look at the specifications of the MacBook as of 2021.

MacBook specification

According to the official website, the MacBook comes with 8GB of memory and 256GB of storage. You can also see that SSD is used as storage device.

Many IT products, like this MacBook, usually have more storage capacity than memory. There are several possible reasons for this, but the main one is that memory is more expensive than storage.

memory is much more expensive than storage

This is the web page to purchase Mac Pro. It turns out that upgrading storage to 1TB costs $400, while upgrading memory to 1.5TB costs a whopping $25,000. Currently, memory is much more expensive than storage, so memory capacity is not as large as storage capacity.


1TB = 1000GB.

In some cases, it is explained that 1TB=1024GB, but that is incorrect. The correct answer is 1TiB=1024GiB.

Questions about Memory

Is Memory Really Necessary?

Is memory needed?

By the way, after listening to the story so far, don't you suddenly have a question like this?
"Do we really need memory originally?"
"If both are devices to store data, can storage alone cover the role of memory?"

Indeed, it seems that even if we want to store data temporarily, we can just save it in storage. But in reality, different hardware, memory and storage, are provided. Why is that?

comparison between memory and storage about speed and capacity

To come to the point, even without memory, storage can logically cover the role of memory. However, storage is much slower than memory to read and write data. Therefore, if even temporary information is written to the storage every time, the computer or smartphone will be extremely slow to respond and become useless for users.

Just as it takes a certain amount of time for humans to remember things over a long period of time, it also takes time for the IT world to store data in storage. This "takes time" means that it takes relatively more time than memory. For this reason, data that only needs to be stored temporarily is stored in faster memory.


There is an area inside the CPU called the "cache" that can read and write data even faster than memory.

What Happens When Running Out of Memory?

Finally, let's talk about memory capacity.

computer slows down

Have you ever experienced that your computer slows down when you launch a lot of software? There are several possible causes for this, and one of them is insufficient memory.

As mentioned in the example, software uses a lot of memory to provide functionality to the user. If you run a lot of software that uses a lot of memory, you will run out of free memory space.

swap in and swap out

When the memory runs out, the data stored in the memory is temporarily moved to a larger storage device to increase the free space in the memory. This is called "swap out". Then, when the data written to the storage is needed, it is read out from the storage to the memory. This is called "swap in".

When there is not enough memory, "swap out" and "swap in", which requires reading and writing to slower storage, occur frequently and slow down the computer. This situation is called "thrashing". This is why it is said that it is better to have a large size memory in order not to slow down the computer.


Finally, I will summarize the contents of the article so far.

In this article, I have explained the differences and characteristics of memory and storage.


Both memory and storage are devices for storing data.

  • "Storage" means that it is used to store persistent data and is non-volatile.
  • "Memory" means that it is used to store temporary data and is volatile.

I also explained the following:

  • Memory can read and write data faster than storage.
  • Storage should have more capacity than memory.
  • Memory is more expensive than storage.
  • Reason why it is better to have a large memory size.

comparison between Memory, SSD and HDD


Thank you for reading the article. Talk to you later!