Maybe this helps a little...
View attachment 2385347
EDIT: Image didn't uploaded correctly...
Eh, disagree on #1 and #5. With those it depends on how the character is portrayed e.g. if #1 makes animal noises instead of speaking, chases after small animals on all fours or primarily eats raw meat I'd still consider them a furry. Likewise if #5 actually is fully sapient, can speak with humans or is a shapeshifter form that's probably furry too (but sex with them should still be tagged "bestiality" too just to be safe). In terms of searching for porn #1 would be called "Kemonomimi", #3 would be "anthro" and #5 would usually be "feral".
For the most part I'd consider (female) furries a subtype of monster girls, an opaque skin-coloured slime girl in a school uniform would still be plenty monstrous too. This excludes humans dressing up in animal costumes ofc which are also called "furries" as a real life community. In terms of tagging most "pet-type" animal girls identified as monster girls would probably fall somewhere between #2 and #4, but for exotic animals or fictional creatures the scope can be much broader. Some sites might also be extra pedantic and make a distinction between "monster" girls for fictional base creatures and "animal" girls for real-life animals, even if the latter is a human-sized cockroach and the former is Soraka.
And I'm pretty sure if one were to have sex with anyone from that picture IRL the real problem would not be the amount of fur but rather the fact
all of them look blatantly underage...
