papillary tumour vs papillary tumor

papillary tumour and papillary tumor both are nouns.

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

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

papillary tumour and papillary tumor: a benign epithelial tumor forming a rounded mass

Other synonyms of papillary tumour include papilloma, villoma.

papillary tumour (noun)	papillary tumor (noun)
a benign epithelial tumor forming a rounded mass	a benign epithelial tumor forming a rounded mass