chemical defence vs Australian spelling

chemical defence and Australian spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
chemical defence	Yes	No	No	No
Australian spelling	Yes	No	No	No

chemical defence (noun)	Australian spelling (noun)
procedures involved in taking defensive measures against attacks using chemical agents	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')