brain tumour vs Australian spelling

brain tumour and Australian spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain tumour	Yes	No	No	No
Australian spelling	Yes	No	No	No

brain tumour (noun)	Australian spelling (noun)
a tumor in the brain	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')