I've recently reset Windows 10 on my computer and reinstalled The Sims 2 using the EA app. I noticed that although Origin always installed it to the x86 folder, the EA app installed it to the regular Program Files. As I understand it, Program Files is for 64-bit programs and x86 is for 32-bit programs, so why would the game now be installed in a different folder if it's the same program? Is this likely to cause any problems or should I just ignore it? Thanks in advance for any advice on this.

Technically, TS2 is a 32-bit program, so by that logic, what it was doing in the x86 folder in the first place is a good question (showed up there for me as well) - could maybe have something to do with the Origin app being a 64-bit program, but who knows.

You can probably just ignore this. If everything is working fine, it's not affecting the game.

By default, the game's install path has always been the x86 program files. Usually TS2, like most apps, will allow you to customize the install path. Typically, I find that it's okay to install smaller apps into program files x64 and x86 alike, though keep in mind that if you decide to modify any of your game files in the install directory, such as if you were installing a lighting mod or clean templates you will require administrator permission to do that from any of the program files locations.

Personally I would've recommended installing the game and the EP/SPs into a new folder location called "Games" on the root of your C: drive as to prevent the game from needing any sort of admin rights, but I suppose as long as the game is working for you and all content for the game is showing up properly when you play then there is little to worry about at this point. Just keep in mind to run the game as administrator!