Shouldn't FOMM do the same thing as the tool ArchiveInvalidated? Or am I totally missing something?

In short after I invalidate using FOMM it should do the same thing right? =/

Yes, because they are the same thing. The original standalone AII! is useful to people who don't use FOMM. The Archive invalidation tool in FOMM is the same thing as the standalone version, just integrated into FOMM.

That's what I thought. But I end up reading old mods on the nexus and it ticks me off I think I know something and I get flustered and second guess what I already know lol

Thanks =)