decolonisation vs British spelling

decolonisation and British spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
decolonisation	Yes	No	No	No
British spelling	Yes	No	No	No

decolonisation (noun)	British spelling (noun)
the action of changing from colonial to independent status	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')