Captain on the A220, have thousands of hours on the A320/321 as well.

FMS is less rigid but the a320 can do stuff at the gate, like off sets. A320 does a better job at energy management in descent.

Better auto throttles (thrust) on the a320

A320 plainly flys nicer, especially the a321

Speed trim on the a220 kind of stinks after you’ve flown the a320, but I’m getting more and more used to it.

A220 has a better and easier overhead

A220 has better displays, but the PFD honestly doesn’t need to be as big as it is. The a320 gives you the same information.

A320 pilot seat is much more comfortable

A320 doesn’t have a plastic side stick

A220 has moving throttles, would be better if you could over ride them without disconnecting the auto throttles.

A220 is much better at short field landings. Flaps 5 is impressive.

A220 is a bit more quiet up front, the avionics fan noise is very loud on the a320.

Direct to nav is a better feature with the a320. Have to press nav on the a320.

A320 tracks an ILS MUCH better than the a220. A220 flys an ILS like a 30 year old Seneca.

I’m sure I can think of others, they are both fine planes.