On which factor, the social difference is mostly based?

The social differences are mostly based on the birth factor, but there are also other factors upon which it depends.

a. Birth: The community, the religion, the caste in which are born.

b. Choices: The way people choose to live, e.g., some prefer going to temples or believe in God while some may not.

c. Religion: The customs or religious practice one follows.

d. Occupation: The work that one wants to do.