serf vs thrall

serf and thrall both are nouns.

Word	Noun	Adjective	Verb	Adverb
serf	Yes	No	No	No
thrall	Yes	No	No	No

As nouns, thrall is a hypernym of serf; that is, thrall is a word with a broader meaning than serf:

serf: (Middle Ages) a person who is bound to the land and owned by the feudal lord
thrall: someone held in bondage

serf (noun)	thrall (noun)
(Middle Ages) a person who is bound to the land and owned by the feudal lord	someone held in bondage
	the state of being under the control of another person