I think there is no difference.
개 is transform (because the machine alter your ticket)
찰 is a note (e.g. a bill)
구 is mouth
If you mix them all together you have "mouth that transforms your bill"
개 is transform
집 is gather
표 is ticket
기 is machine
literally "machine that gathers and transforms tickets"
I am not native so you could prefer one word to the other depending on the context. I need someone to confirm that too (as a guess I would say 개찰구 is more used because it's shorter and 구 means "mouth" or "entrance" and implies a direction. While 개집표기 sounds more technical).