profit margin vs ratio

profit margin and ratio both are nouns.

Word	Noun	Adjective	Verb	Adverb
profit margin	Yes	No	No	No
ratio	Yes	No	No	No

As nouns, ratio is a hypernym of profit margin; that is, ratio is a word with a broader meaning than profit margin:

profit margin: the ratio gross profits divided by net sales
ratio: the relative magnitudes of two quantities (usually expressed as a quotient)

profit margin (noun)	ratio (noun)
the ratio gross profits divided by net sales	the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree
	the relative magnitudes of two quantities (usually expressed as a quotient)