I assume you mean the difference between a 32 and and a 321.
Mostly it is a matter of detailed things.
Early 32s had a 29hp engine I think. All 321s have a 39hp engine.
321s had the option of a deeper keel with a bulb (1.8m) with a taller mast. So more sail power.
I think all 32s have an inside wheel, whilst 321s have an option of a ‘nav station’ for having a PC and an autopilot control. The structure is lower and you have a seat to sit at the computer.
The side windows are different.
321s have an extended bit of superstructure where it slopes down to meet the cockpit coamings. This makes it very comfortable because 2 people can sit ‘in the corners’ of the cockpit completely sheltered.
Bathing ladder moved to the side.
That being said, I have a 2002 321 with taller rig and deep keel, but over the years the 321s have had other detailed improvements.
Hope that helps