The JV-880 module is similar to the JV-1000 keyboard, but there are a few differences. The JV-880 has 2 banks of ROM Patches while the JV-1000 has the same 2 plus an additional 4 banks. Also, the JV-1000 can be expanded with the VE-GS1 Sound Canvas expansion board and it has a built-in sequencer. The JV-880 has a similar structure (8 part multitimbral, 28 voice polyphonic, same Patch structure) to the JV-1000 but contains less waveforms.
Other similar sound modules are the JV-1080 and JV-2080. Both have 16 part multitimbral capability, 64 voice polyphony and an expanded JV sound engine. The JV-1080 has 512 on-board patches and can accommodate up to 4 SR-JV80 wave expansion boards while the JV-2080 has 640 on-board patches and can accommodate up to 8 SR-JV80 wave expansion boards.
Owner's Manual: https://www.roland.com/us/support/manual_archive/