Almost every release has multiple versions and I'd like to know what each means but am having trouble finding info about it.

Generally x86 means 32bit, but there are both arm and arm64 which normally means arm would also be 32bit and arm64 is the 64bit one?
I don't even know what arm means in this context.
Mod generally means something was modified but most of the releases I've seen don't list what modifications were made.

So I'm not sure which version is best to use for me, or even which version i should be installing.

Also, when installing games, do you need both the apk and obb files?

Thanks in advance for taking the time to help a newb out.

Since no one responded I continued searching and found that arm is the instruction set that most android cpu's, like snapdragon, use, and that arm64 is the version that I (and most people) should be downloading. I've decided to only download the mod version if the comments or OP talk about how the mod version is different.

And I also now know that the obb file is required for games.

Maybe other new people that are confused about what version to download will see this and be less confused