Facebook seems to hide away the meaning of those terms when creating Audiences for ads.
I just want to know - do those terms refer to apps/pages' numerical IDs or to users' numerical IDs (like 4 for Mark Zuckerberg)? And if it's the latter, what's the difference between the two terms?
The closest Facebook agrees to reveal is https://www.facebook.com/business/help/606443329504150 which mentions only the first term and even then doesn't answer my question.