benign tumour vs tumor

benign tumour and tumor both are nouns.

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

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

Other hypernyms of benign tumour include neoplasm, tumour.

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