benign tumor vs nonmalignant tumour

benign tumor and nonmalignant tumour both are nouns.

Word	Noun	Adjective	Verb	Adverb
benign tumor	Yes	No	No	No
nonmalignant tumour	Yes	No	No	No

As nouns, benign tumor and nonmalignant tumour are synonyms defined as:

Other synonyms of benign tumor include benign tumour, nonmalignant neoplasm, nonmalignant tumor.

benign tumor (noun)	nonmalignant tumour (noun)
a tumor that is not cancerous	a tumor that is not cancerous