In terms of graduate schools, or future careers. I’ve read many threads and perused many school websites on the BA/BM subject, so I know what each technically entails (classes, etc.) - I’m asking more about opportunities after.
Most opportunities after your BA/BM are audition based. You don’t even need a degree in music to go on if you get adequate instruction and practice. You might be behind in course work for a MM but that just means you will take longer getting that degree while you make up the classes. So when evaluating the BA/BM look beyond the courses to what your instruction, practice, and performance opportunities are.
It all depends on the student and how much preparation they need. A BA in music will generally have less music oriented classes and more liberal arts classes than a BM, you might have less theory classes ear training and so forth, though obviously that depends on the program, and you will have the core courses that BM students often don’t have to take (it depends on the school, again).You also will likely have less ensemble work with a BA then a BM…and I seem to recall that some schools who offer both BA and BM programs, that the BA students may not be able to play in the orchestras and ensembles the BM students do, and that could be a problem, if the ensembles you got into as a BA weren’t quite that high level…
I don’t think a BA degree closes doors, if someone can get their technique up to shape given the time spent away from music with a BA, if they have solid technique and repertoire, if going to graduate school that is all that is going to matter. The reason a BA would close doors IMO isn’t because it is a BA degree, ti is for a particular student that a BA didn’t work for them, there wasn’t enough music to drive them forward. There have been people who didn’t get a BM degree or a BA degree, get a degree from a school with a solid music program (like an Ivy), work with a private teacher and so forth, and get into grad school for an MM…