promontory vs headland

promontory and headland both are nouns.

Word	Noun	Adjective	Verb	Adverb
promontory	Yes	No	No	No
headland	Yes	No	No	No

As nouns, promontory and headland are synonyms defined as:

promontory and headland: a natural elevation (especially a rocky one that juts out into the sea)

Other synonyms of promontory include foreland, head.

promontory (noun)	headland (noun)
a natural elevation (especially a rocky one that juts out into the sea)	a natural elevation (especially a rocky one that juts out into the sea)