So here's the deal, the MSPE (deans letter) will typically contain whether the person is Sr AOA v Jr AOA. But whether or not sr v jr matters is difficult to ascertain. Based on some of the match data out there 68% of the PDs said that AOA status mattered for when they were selecting people to interview. That being said, only 27% of people who match in Ortho are AOA and 6% of people applying for ortho that are AOA don't match. AOA also got a 3.8/5 rating for importance in ranking a person. There are a plethora of things that were ranked higher than this, like interpersonal skills, interaction with housestaff, grades, usmle scores, LOR, color of necktie...
In my experience the answer is simple - there is no rhyme or reason for different programs offering interviews to certain candidates vs others. Me and my buddy who went to the same med school, had essentially identical grades, I was Jr AOA he was Sr AOA, our step scores were essentially the same and we applied to almost all the same schools. We got offers from different schools for no reasons we could understand. He got some offers from "more competitive" programs that i didn't, i got some he didn't. Both matched.
Once you're sitting on the other side of the match list you realize that it's very program specific, and it's all arbitrary, and you wonder what was said about you when you were coming through.
1