feudalism vs feudal system

feudalism and feudal system both are nouns.

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

As nouns, feudalism and feudal system are synonyms defined as:

feudalism and 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

feudalism (noun)	feudal system (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 social system that developed in Europe in the 8th century; vassals were protected by lords who they had to serve in war