Airbus CCQ
In a previous airline the A319/A320/A321 were all flown as 'one type'.
There were, I think 6 variants within those three aircraft due to leased aircraft with different engines, weights, systems powered in the EMER CONFIG, cabin seating, etc. There was an A5 sized sheet of differences placed near the Capt's window for that particular model so a self-brief could be accomplished.
It was not uncommon to fly all three in one duty period.
CK