mar vs birthmark

mar and birthmark both are nouns.

Word	Noun	Adjective	Verb	Adverb
mar	Yes	No	Yes	No
birthmark	Yes	No	No	No

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

mar: a mark or flaw that spoils the appearance of something (especially on a person's body)
birthmark: a blemish on the skin that is formed before birth

mar (noun)	birthmark (noun)
a mark or flaw that spoils the appearance of something (especially on a person's body)	a blemish on the skin that is formed before birth

mar (verb)	birthmark (verb)
destroy or injure severely
make imperfect