feudalism vs social structure

feudalism and social structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
feudalism	Yes	No	No	No
social structure	Yes	No	No	No

As nouns, social structure is a hypernym of feudalism; that is, social structure is a word with a broader meaning than feudalism:

feudalism: the social system that developed in Europe in the 8th century; vassals were protected by lords who they had to serve in war
social structure: the people in a society considered as a system organized by a characteristic pattern of relationships

Other hypernyms of feudalism include social organisation, social organization, social system, structure.

feudalism (noun)	social structure (noun)
the social system that developed in Europe in the 8th century; vassals were protected by lords who they had to serve in war	the people in a society considered as a system organized by a characteristic pattern of relationships