feudal system vs structure

feudal system and structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
feudal system	Yes	No	No	No
structure	Yes	No	Yes	No

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

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

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

feudal system (noun)	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	a thing constructed; a complex entity constructed of many parts
	the manner of construction of something and the arrangement of its parts
	a particular complex anatomical part of a living thing and its construction and arrangement
	the complex composition of knowledge as elements and their combinations
	the people in a society considered as a system organized by a characteristic pattern of relationships

feudal system (verb)	structure (verb)
	give a structure to