utilisation vs usage

utilisation and usage both are nouns.

Word	Noun	Adjective	Verb	Adverb
utilisation	Yes	No	No	No
usage	Yes	No	No	No

As nouns, utilisation and usage are synonyms defined as:

Other synonyms of utilisation include employment, exercise, use, utilization.

utilisation (noun)	usage (noun)
the act of using	the act of using
	accepted or habitual practice
	the customary manner in which a language (or a form of a language) is spoken or written