nonmalignant tumor vs nonmalignant tumour

nonmalignant tumor and nonmalignant tumour both are nouns.

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

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

nonmalignant tumor and nonmalignant tumour: a tumor that is not cancerous

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

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