Why is the ISO size different for Tech bench and MCT?

I downloaded Windows 10 64bit International English from techbench and the size is 4.09GB
In both cases I selected Windows 10(not home or pro or single language or n or kn just Windows 10)
Language:British English(english international)
64bit
I created same iso using MCT and size is 3.38 GB.
Why is there such a size difference?
I compared the two iso using Winmerge and these difference showed up::




Left: iso from techbench
Right: iso from MCT

The difference: 1) In sources folder techbench has Install.wim which is 3.59 GB while MCT has Install.ESD which is 2.87 GB

2)In sources folder techbench Boot.wim is 274,678 KB while MCT Boot.wim is 274,627 KB
3)In sources folder techbench iso has no ws.dat file while MCT has ws.dat file.
4)In root folder techbench iso has no MediaMeta.xml file while MCT iso contains it.

Download location for Techbench iso:https://www.microsoft.com/en-us/soft...load/techbench
Download location for MCT: https://www.microsoft.com/en-us/soft...load/windows10

Install.esd is a more compressed version than install.wim.

There is no difference although one may have more recent updates than the other included. Makes no difference as install updates quickly to latest version.