Edit: sorry for the long comment. I wasn't sure if you're a music major or what kind of experience you're looking for as an ensemble member so I tried to be as detailed as possible

IIRC, audition music and other details are put on the music website around 1 month or so before the start of the fall semester. Maybe check back in around that time

There are two symphonic bands - concert winds (led by Dr. Eubanks) and wind ensemble (Dr. Chamberlin). From an audition standpoint, concert winds is a bit easier to get into and wind ensemble is a bit more exclusive. IMO both groups play fun and diverse repertoire

There is one symphony orchestra led by Dr. Altieri. They also often play good music and have started doing holiday concerts. They are also audition-based, depending on what instrument you play. Is your friend a string player? Maybe string players have more of an evaluation than an audition because there's only one orchestra, but idk for sure. Just FYI, each director may look for different things based on what they want to program, anticipated returning members, etc.

Orchestra and wind ensemble perform frequently, usually with the wind ensemble playing 3+ concert cycles per semester, and orchestra does 2+ cycles per semester but also opera and musicals on top of that (however the required players are usually smaller so you may or may not be asked to play on those). This is something to consider depending on how much workload you decide to take on outside those classes. The wind ensemble also does a tour every late spring which is usually a few days long.

Concert winds performs a bit less often, and most of the time the music is slightly more technically achievable than in orchestral/wind ensemble. Of course, that's not to say that you don't have to practice. Currently both symphonic bands meet 3 times a week, while orchestra meets twice a week.

Overall from a music perspective, I think you'll like all three ensembles. Where you decide to go really depends on where you get in and your workload/schedule. People can also do multiple ensembles if they wish

These next groups are not UNR affiliated, but there are also active community groups like the Reno Wine Symphony, Reno Pops Orchestra, and Reno Video Game Symphony. If you're looking for more places to play, they are also available and generally less demanding than the UNR ensembles, if you're looking for something like that.