vassalage vs thralldom

vassalage and thralldom both are nouns.

Word	Noun	Adjective	Verb	Adverb
vassalage	Yes	No	No	No
thralldom	Yes	No	No	No

As nouns, thralldom is a hypernym of vassalage; that is, thralldom is a word with a broader meaning than vassalage:

Other hypernyms of vassalage include bondage, slavery, thraldom, thrall.

vassalage (noun)	thralldom (noun)
the state of a serf	the state of being under the control of another person