benign tumour vs nonmalignant tumor

benign tumour and nonmalignant tumor both are nouns.

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

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

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

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