margin of profit vs profit margin

margin of profit and profit margin both are nouns.

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

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

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

Other synonyms of margin of profit include gross margin.

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