square kilometre vs Australian spelling

square kilometre and Australian spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
square kilometre	Yes	No	No	No
Australian spelling	Yes	No	No	No

square kilometre (noun)	Australian spelling (noun)
a decimal multiple of the unit of surface area, the square metre, equal to 1,000,000 square meters.	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')