In a normal coach, AC 3 Tier Seats (berths) (leave apart New Rajdhani and Garib Rath Trains) are 64 while AC 2 Tier (leave apart new Rajdhani) seats (berths) are only 46.
Side Berths are two tier in both type of the coaches while cabin berths are 6 in 3 Tier and 4 in Two Tier.
In 3 Tier, only windows used to have curtains (now, provision has been there to cover the seats also with curtains in 3 tier coaches) but in 2 tier the Cabin and side berths do also...
more... have Curtains.
2 Tier has reading lamps on all the berths.