What qualifies as (not) translatable?

Unless I'm blind, I didn't see this in the archives...I'm thinking of writing a couple of tutorials here and there for making icons in PSPXI. However, I'm not familiar with Photoshop - what cannot be translated from PSPXI to PS? Is there anything? (There's the whole selective coloring thing unique to only PS, but I don't need to know what can't be translated the other way around.) Furthermore, is there anything that cannot be translated from PSPXI to older versions of PSP?

Thanks in advance!

EDIT: Thanks, guys, you've been a lot of help!