stretch mark vs striation

stretch mark and striation both are nouns.

Word	Noun	Adjective	Verb	Adverb
stretch mark	Yes	No	No	No
striation	Yes	No	No	No

As nouns, striation is a hypernym of stretch mark; that is, striation is a word with a broader meaning than stretch mark:

stretch mark: a narrow band resulting from tension on the skin (as on abdominal skin after pregnancy)
striation: a stripe or stripes of contrasting color

Other hypernyms of stretch mark include band, banding, stria.

stretch mark (noun)	striation (noun)
a narrow band resulting from tension on the skin (as on abdominal skin after pregnancy)	a stripe or stripes of contrasting color
	any of a number of tiny parallel grooves such as: the scratches left by a glacier on rocks or the streaks or ridges in muscle tissue