benign tumor vs tumour

benign tumor and tumour both are nouns.

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

As nouns, tumour is a hypernym of benign tumor; that is, tumour is a word with a broader meaning than benign tumor:

Other hypernyms of benign tumor include neoplasm, tumor.

benign tumor (noun)	tumour (noun)
a tumor that is not cancerous	an abnormal new mass of tissue that serves no purpose