tribal chief vs headman

tribal chief and headman both are nouns.

Word	Noun	Adjective	Verb	Adverb
tribal chief	Yes	No	No	No
headman	Yes	No	No	No

As nouns, tribal chief and headman are synonyms defined as:

Other synonyms of tribal chief include chief, chieftain.

tribal chief (noun)	headman (noun)
the head of a tribe or clan	the head of a tribe or clan
	an executioner who beheads the condemned person