Nope, seems not obviously different.
Don't put so much weight on deciphering version numbers. There is no law that it has to make sense.
Facebook 7.0 was released just weeks ago with just "bug fixes" and nothing else it seems. So far it looks like Facebook just kind of took the whole version numbering system and threw it in the garbage simply assuaging a new major version to pretty much every release no matter what it is (even just some bug fixes).i agree but there is an unwritten rule that when the number before the "." is moved higher that there are more major/visual changes than minor ones/bug fixes.
facebook 8.0 doesn't seem to be a major update.
Every time i see updates for facebook I'm hoping bug when i tap on the post or picture "I don't want to see this" it still stays. I'm guessing that they don't consider this as a bug. But for me its most annoying bug.