Alright, probably a stupid question that most people had the answer to years ago, but the Xbox One is 100% region free for games right?

I ask because I ordered a couple of games on disc from Amazon and they sent me European editions of the games (at least I think they're European, they have PEGI ratings instead of ESRB ratings). Would the experience of playing these games on my American Xbox be at all different than if I were playing domestic copies of the games? I have zero experience dealing with import copies or anything like that.

Should be no problem at all. On Xbox (this counts for 360 as that's where I've had my import experience from) I've never had an issue with buying a US copy of a game and playing on my EU console even when it comes to DLC. The Xbox store seems to operate with the same version across regions unlike PSN where if you bought a US copy and tried to download a DLC pack for the game from an EU store it would not recognize it.

The games on all consoles this generation are region free and the vast majority of them, unless they're Japanese releases at least, all have English as one of the languages in addition to the larger European ones. So if the language on the back of the box is in English you should most definitely be safe to use an EU game on an US console.