saltpetre vs Australian spelling

saltpetre and Australian spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
saltpetre	Yes	No	No	No
Australian spelling	Yes	No	No	No

saltpetre (noun)	Australian spelling (noun)
(KNO3) used especially as a fertilizer and explosive	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')