Windows 11 ISO differences? MCT vs ISO image?

When I go to download the latest Windows 11 ISO from here, what is different in the ISO image from the one you download through the Media Creation Tool (MCT) or download the ISO images (i.e. Win11_25H2_English_x64_v2.iso)?

One difference I have always noticed, and not sure of the meaning of it, the Windows.iso image downloaded through the MCT has the install.esd image file while the download ISO image has the install.wim file. Just not sure of the differences.

If this has already been documented on here somewhere, I must have missed it.
Thanks.

Mark K said:

If this has already been documented on here somewhere, I must have missed it.
Thanks.

Click to expand...

I got my answer from Copilot.

Basically, same image, the install.esd/install.wim files difference, and the ISO image provides more editions. The ISO file is not updated very often while the ISO generated through the MCT updates frequently now by Microsoft.

Mark K said:

When I go to download the latest Windows 11 ISO from here, what is different in the ISO image from the one you download through the Media Creation Tool (MCT) or download the ISO images (i.e. Win11_25H2_English_x64_v2.iso)?

One difference I have always noticed, and not sure of the meaning of it, the Windows.iso image downloaded through the MCT has the install.esd image file while the download ISO image has the install.wim file. Just not sure of the differences.

Click to expand...

Yes, the MCT makes an ISO with an install,esd while the directly downloaded ISO contains an install.wim. There is no practical difference if all you want to use it for is to install Windows, but if you want to create a custom install by adding or removing items using DISM then you need the install.wim.

The .esd format uses stronger compression than the .wim format, so the .wim is always larger. It's larger still because it contains additional editions. For example, Windows 11 Pro for Workstations is only available in the install.wim of the direct download ISO. You can use DISM to list the editions contained in your ISO.

Find Build and Version of Windows 11 Installation ISO or USB

Another consideration is what build of Windows is in the ISO. Microsoft regularly update the MCT to make a newer build, while the directly downloaded ISO is only infrequently updated. The MCT has been updated quite a few times since the release of 25H2. The direct ISO for 25H2 has just been updated the once, hence the 'v2' in its name. Currently they both are for 25H2 build 26200.8037, but the MCT may get another update in a month or so.

This tutorial is regularly updated to include the build number that each option currently contains.

Download Official Windows 11 ISO file from Microsoft

Bree said:

Another consideration is what build of Windows is in the ISO. Microsoft regularly update the MCT to make a newer build, while the directly downloaded ISO is only infrequently updated. The MCT has been updated quite a few times since the release of 25H2. The direct ISO for 25H2 has just been updated the once, hence the 'v2' in its name. Currently they both are for 25H2 build 26200.8037, but the MCT may get another update in a month or so.

Click to expand...

I have always downloaded the ISO through the MCT to create the USB flash drive installs. Someone asked me about the ISO download, that caught me off guard a bit, and I just told the person that it is best to download through the MCT.

Thank you for providing the information.

Mark K said:

I have always downloaded the ISO through the MCT to create the USB flash drive installs. Someone asked me about the ISO download, that caught me off guard a bit, and I just told the person that it is best to download through the MCT.

Click to expand...

If you make an ISO file with the MCT it contains an install.esd. It used to be the case that the install.esd was less than the 4GB file size limit for Fat32, so I used to download the ISO, mount it, and copy everything to a USB to make my install USB. The install.esd for 25H2 is now 5.37GB, so if you want to make an install USB you must make it directly with the MCT. It will split the install.esd into two parts, an install.swm and an install2.swm (Split Windows iMage file), both less than the 4GB limit of an install USB's Fat32 partition.

The MCT version uses install.esd (smaller), while the downloadable ISO uses install.wim. Here's why I use iso.
An iso is multi-edition and can be used to install/repair windows on any machine and is easier to work with when integrating drivers or customizing the image.
One must use iso when installing on VM or wants to use Rufus to bypass hardware requirements or have control of GPT/MBR.

MCT requires a working Windows, ISO does not. MCT can create a corrupted ISO, you will never know, but issues will follow.
MS releases updated ISO every month. A signature can be checked to make sure, that it is genuine, not made with MCT.

Bree said:

if all you want to use it for is to install Windows, but if you want to create a custom install by adding or removing items using DISM then you need the install.wim.

Click to expand...

Can mount .esd files since dism version 26100.6584. Presumably the mounted image can be serviced though I havent tried

The latest win11 iso I have the install.wim is 6.54gb. Dont know how big the equivalent .esd would be.

SIW2 said:

Can mount .esd files since dism version 26100.6584. Presumably the mounted image can be serviced though I havent tried

Click to expand...

You can't service a mounted ESD image, but you can do a repair install from one.

SIW2 said:

The latest win11 iso I have the install.wim is 6.54gb. Dont know how big the equivalent .esd would be.

Click to expand...

The ISO has just been re-released as 'v2' with build 26200.8037. The install.wim in my Win11_25H2_EnglishInternational_x64_v2.iso is 7.06GB. The install.esd for 25H2 26200.8037 is 5.37GB.