employment vs usage

employment and usage both are nouns.

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

As nouns, employment and usage are synonyms defined as:

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

employment (noun)	usage (noun)
the occupation for which you are paid	the act of using
the act of using	accepted or habitual practice
the act of giving someone a job	the customary manner in which a language (or a form of a language) is spoken or written
the state of being employed or having a job