headland vs mull

headland and mull both are nouns.

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

As nouns, mull is a hyponym of headland; that is, mull is a word with a more specific, narrower meaning than headland:

headland: a natural elevation (especially a rocky one that juts out into the sea)
mull: a term used in Scottish names of promontories

Other hyponyms of headland include point.

headland (noun)	mull (noun)
a natural elevation (especially a rocky one that juts out into the sea)	a term used in Scottish names of promontories

headland (verb)	mull (verb)
	reflect deeply on a subject
	heat with sugar and spices to make a hot drink