Social class and Underclass

Social class noun - People having the same social, economic, or educational status.

Underclass and social class are semantically related. In some cases you can replace term "Underclass" with "Social class", this terms are similar.

Underclass noun - The social class lowest in the social hierarchy.

Social class and underclass are semantically related. Sometimes you can use "Social class" instead a noun "Underclass".