In America there is no system in place today that forces people to remain separate or keeps one Class subservient to another.
If you were born the son of a street sweeper, but excelled, you could become a doctor or lawyer or some celebrity or entrepreneur - and at the same time you would be fully accepted by your peers.
Not so in India. The Caste system freezes everyone in place. It is extremely difficult - almost impossible - for someone from the lowest Caste to rise in education and social status.
An Indian Untouchable would never be allowed to marry into one of the higher Castes and would never be accepted as an equal.
And for an Indian Untouchable to make it into medical school or opening a restaurant or become a priest in a temple or become a member of high society in India is very rare indeed.