Actually Rockhen's comments would almost equally apply to the pipe organ - or even most multi-keyboard 'electronic organs'.

The only thing in common is the keyboard.

In other threads here I mentioned a recent invention about a gadget that is a shell that looks like a grand piano for 'keyboards'.

I'm no piano accordion expert, just a recycled multi-instrumentalist muso who knows a few tricks - I also try to learn as much as I can from other musos, in person or thru books, tapes, video, etc...

There is another things about 'keyboards' - the physical 'thing' that is.

Pianos (actually pianofortes!) have a totally different 'touch' from a keyboard on a harpsichord, pipe organ, piano accordion, 'midi keyboard', etc. The latter are mostly 'on-off' switches.

'Piano-fortes' have 'variable touch' - and the hundreds of designs of actions are various attempts to to refine this.

It was probably due to my slight MMD that I found that 'non-pianofortes' were more my kind of instrument.

The more expensive 'electronic keyboards' have 'velocity sensitive' action - which attempts to emulate a 'piano-forte' action.