Social class and Three estates

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

Three estates and social class are semantically related. In some cases you can replace phrase "Three estates" with "Social class", this phrases are similar.

Three estates noun - A major social class or order of persons regarded collectively as part of the body politic of the country (especially in the United Kingdom) and formerly possessing distinct political rights.

Social class and three estates are semantically related. You can use "Social class" instead a noun phrase "Three estates".