The App Store has the Microsoft 365 versions - you need to have a 365 subscription to activate them, which is why they are listed in the App Store as "in App purchase." It's the versions of Word and Excel which I use.I guess that the apps on the App Store are free versions.
The Office apps in the App Store are the full apps. You can either subscribe through the apps or sign in using your existing Microsoft 365 subscription, if you have one. You cannot use these downloads with the standalone Office license, however.I mean full-licensed Office apps. I guess that the apps on the App Store are free versions.