Although both of them are equally entertaining, 7d cinema will give you a feel of being one of the characters in the film. The screen is more prominent in size, so is the sound system. The chairs vibrate with your action scenes, and they even smell like popcorn to make you feel that you are sitting in an actual theatre.
7mbc gives you the same experience as watching a movie at home, but with a more comfortable environment. It is also cheaper than 7d cinema because it requires less maintenance and infrastructure, such as a sound system and vibration chair.