Take a look at his thread that seem to have a lot of info regarding differences between the two

Location: Denmark

Beocenter 9500 every time. Beocentral explains it, and isn’t very complimentary about the 9300! - https://beocentral.com/beocenter9300  

Ah thank you, I had no idea the internals were so very different in the 9300. I don't think I'll ever have use for the 2-way remote capability of the 9500.  I have a two Beo6 remotes but my understanding is that while that is a 2-way remote, that's not compatible with the 2-way system in the 9500.  I think the 2-way functionality of a Beo6 is only for the BS5 Encore (which I don't own). However, the lack of a phono stage in the 9300 is a deal breaker - I'll make sure I look for a 9500 instead then, not a 9300. I've restored a few in this range before (8000, 8500 and 9000) so it'd also help me that the 9500 has many of the same components that I'm familiar with, unlike the 9300. Thanks both for your help.

Also worth noting is that the BC9500 has both a phono and a tape2 connection where the BC9300 use the same connection for both of these commands

I got hold of a Beocenter 9500 pretty cheap because it needed new tape belts (I know I can fix that though, done it before), and it has a cracked glass panel but otherwise in great condition.  I'll find a new glass panel for it, given time. However, it also suffers from another common problem - the Speakers 1 outputs don't work.  I know this will be due to a faulty mute relay, but I'm useless with a soldering iron and my last attempt to fix that same issue in an old BC9000 only made it worse. However, I do have a full amplifier component from a Beocenter 8500 which I stripped down for parts a while ago.  Can anyone tell me if the BC9500 and BC8500 amplifiers are the same? I intend to use the BC9500 with active Beolabs, but all the same, it'd be nice to have it fully working.