Question: what is the difference between 3 tier and 2 tier?
Answer: So a 3 tier AC is a normal sleeper coach with AC. It has a total of 72 seats normally in a coach. 3 berths on 1 side, one above the other (Lower berth, Middle berth & Upper berth). A 2 tier AC is a AC coach with 2 berths on 1 side, one above the other (Lower berth & Upper berth).