I think there is no difference. 개찰구 : 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" 개집표기 : 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).

hi