Nanofilm: Your comment "same in the sect of Muslims although religion is one" is totally off-center, incorrect and reflects your shallow knowledge of Islam.
The caste system as prevalent in Hinduism is based on social standing, heredity and ethnicity. To my knowledge, a person of a lower caste in India is not allowed to eat in the same plate or drink from the same glass that is in use by someone from the higher caste such as a Brahman let alone marry. Caste is a SOCIAL position. Caste is something you are b-o-r-n into and one just c-a-n-n-o-t change it.
Sect, on the other hand, is division of a religion. Sect is like a denomination. It is the difference in how one views and practices religion. People belonging to the two major sects in Islam Sunni and Shia do eat together in the same plate and even marriages take place between individuals belonging to the two sects. Also, people can convert to a Sunni from a Shia and vice versa and there are no restrictions in doing so.