desensitisation vs desensitization

desensitisation and desensitization both are nouns.

Word	Noun	Adjective	Verb	Adverb
desensitisation	Yes	No	No	No
desensitization	Yes	No	No	No

As nouns, desensitisation and desensitization are synonyms defined as:

desensitisation and desensitization: the process of reducing sensitivity

desensitisation (noun)	desensitization (noun)
the process of reducing sensitivity	the process of reducing sensitivity