gross margin vs margin of profit

gross margin and margin of profit both are nouns.

Word	Noun	Adjective	Verb	Adverb
gross margin	Yes	No	No	No
margin of profit	Yes	No	No	No

As nouns, gross margin and margin of profit are synonyms defined as:

gross margin and margin of profit: the ratio gross profits divided by net sales

Other synonyms of gross margin include profit margin.

gross margin (noun)	margin of profit (noun)
the ratio gross profits divided by net sales	the ratio gross profits divided by net sales