While ‘race’ (as a social construct) is a way of classifying people into groups based on physical traits, ‘caste’ is a system of social stratification, where groups are assigned a way of life defined primarily by occupation.
Caste has no distinguishable physical feature and members of the same ‘race’ group may be of several different caste groups. In Britain for example, Dalits have progressed economically and do not follow their traditional occupations of cleaning toilets and skinning dead animals, but they encounter caste-based discrimination in social interactions. Unlike race discrimination, caste discrimination is intra-racial and is practised among those of the same nationality, ethnic origin and/or cultural background.