Thank you! She's an adult (~6 yrs) and a recent adoptee. And has a super fluffy butt. I don't have a ton of pictures yet (they're super nervous) but here are a few:pretty sure it depends on the body shape and feather distribution. an australorp should be slimmer and longer looking if that makes sense? and a black orpington should be rounder looking with poofier feathers near the rear. that’s as best as i can describe it. not sure how you could tell th difference in the chicks though. maybe if you posted pictures we’d be able to help!