benign tumour vs nonmalignant tumour

benign tumour and nonmalignant tumour both are nouns.

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

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

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

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