Both versions are written by Apple.
The copy from the Microsoft store automatically updates, whereas the version directly from Apple requires the user (that's you) to actively cause iTunes to update.
- In the copy from Apple, either you periodically check for updates and act upon any messages you see, or when iTunes itself tells you there's an update available, you have to agree to it being downloaded. It can be used on earlier versions of Windows (such as Windows 7)
- With the copy from Microsoft, you don't have to do anything, except get very annoyed with it when it:
- doesn't work
- causes you to realise that features appear to be missing from it
- updates at an inconvenient time. Now, I don't know for certain that iTunes does this, but by default Windows 10 does update whenever it feels like it, even if you're in the middle of the most important presentation of your life. (I specifically stopped my Window 10 from doing this, once I "discovered" that such a reasonable idea was possible. Microsoft don't happen to tell you about any of this until it's too late)
Oh - and the Microsoft Store version is for Windows 10, the implication being that it cannot be used on Windows 7. Not the most tragic thing then!
If you are already familiar with using iTunes, there appears to be plenty of things to trip you up with the Microsoft Store version; from what I've read, wondering why you can't find the "update iTunes" button for starters.
So I'm not surprised that the Microsoft version gets a low score. It's a pile of something you wouldn't want to tread in when wearing your best shoes. For example, soft, soggy mud on a rainy day (of which, we get lots in the UK).