occupant vs occupier

occupant and occupier both are nouns.

Word	Noun	Adjective	Verb	Adverb
occupant	Yes	No	No	No
occupier	Yes	No	No	No

As nouns, occupant and occupier are synonyms defined as:

occupant and occupier: someone who lives at a particular place for a prolonged period or who was born there

Other synonyms of occupant include resident.

occupant (noun)	occupier (noun)
someone who lives at a particular place for a prolonged period or who was born there	someone who lives at a particular place for a prolonged period or who was born there
	a member of a military force who is residing in a conquered foreign country