This will be a pretty big step up from my current one, and since I've been playing for almost a year now and I know I'm going to stick with it I think it's safe to upgrade.
Five treble rows instead of three. I learned on three rows of buttons, which is a good idea because those are the main rows for fingering and you won't pick up any bad habits if you only have those main rows. But the two extra rows give additional options for tough fingerings so it's nice to have them now that I know when it's appropriate to use them
Six bass rows instead of five. My current bayan is the simpler folk instrument type, which doesn't have buttons for diminished chords. That actually limits the songs I'm able to play, so this is probably the most significant upgrade
Five treble registers instead of two. My current bayan only has clarinet and wet violin registers. The new one has clarinet and wet violin still, but adds a 4' reed bank and so can do accordion, bandoneon, and bassoon registers
Two bass registers instead of one. I'm actually not sure what the registers are, but there's only two reed banks so it's gotta be single and octave doubled
An air button! My current bayan doesn't have one, so to close the bellows without making a sound you have to hold down as many buttons as possible while closing it slowly so there's not enough airflow to sound any of the reeds. Which is doable but very tedious lol
A bellows strap. This just holds the bellows closed, which is nice because actuating the bellows when the valves are closed can damage the valves. Makes picking it up and transporting it a lot easier
And finally: the buttonboard is flush with the back plate. My current bayan has the buttonboard in the middle of the treble case, so when I play with five fingers (and I'm not using my thumb to support the buttonboard) there's a lever action that causes the edge of the treble case to dig into my sternum. Which is both painful and also tilts the buttonboard into an uncomfortable position. I've gotten good enough that playing with five fingers is common so this is actually the biggest problem I have with my current instrument. I've tried all kinds of strap positions, postures, seat heights, and even bought expensive straps to try to work around this issue but I think it's just intrinsic to the design or my body type or something because I can NOT get it to not do that 😩
Anyway, my first bayan was about $400 shipped and this one's a bit over $800 (both are used but restored, QA'd, tuned, etc.). So still very much in the "beginner instrument" tier, but hopefully a big step up from what I've been working with!