What's the story difference between PSP2 and PSP2 Infinity?

Is Inifinity a sequel like AoTI to PSU or does infinity include all of the PSP2 story and just adds some more story on top?

Pretty sure Infinity just an add-on for PSP2. Like an expansion. So similar to AoTI to PSU

Thanks for the utterly useless post.
No really, it made me check the PSP wikia and now I know for a fact that Infinity is a full fledged sequel to PSP 2 and not just a bit of added story.

There is no need to be rude just because they didn't give you a fully correct answer; that just makes people less likely to actually want to help you if that's how you'll respond.
PSP2i is not a full, standalone sequel, rather it is an enhanced version of PSP2 with a new race, new weapons, new systems, and a second story episode (akin to how PSO Ep.I&II is an enhanced version of the Dreamcast version of PSO), and you can import your saved game from the original PSP2 and can use its DLC. Essentially, it is a bundle of the original game and an expansion.
https://i.imgur.com/YvzZvDu.png
Episode 1 is the original story of PSP2.
Episode 2 is the new story content that takes place 1 year after the story of Episode 1.