What are the similarities and differences between the caste system in India and the class system of the contemporary United States?

The class system in the United States is very rigid, there is no doubt about it. It is very difficult to be born into poverty and eventually become wealthy in your lifetime. The major distinction between the caste and class system are the words "very difficult" in the previous sentence. In a caste system, it is not even possible to be born into one caste and move to the next. The caste system guarantees that people are born into a caste and must perform the duties of that caste for their entire life. Only by performing these duties admirably, can a person hope to increase their lot in the next life through reincarnation. In the United States, some members of the lower classes, through hard work, education and luck can move to the middle or upper classes. While this should not be considered common, it is quite possible and does happen. The same can be said of wealthy people that make poor decisions and end up in the lower classes.  The caste system is also closely tied to the religion of Hinduism and not such religious connection exists in the American class system.  

The major similarities between the caste system and American class system are the difficulty for social mobility and how the caste or class limits the potential success of its members.  Both are systems to organize and control different parts of the population.