life-sized vs lifesize

life-sized and lifesize both are adjectives.

Word	Noun	Adjective	Verb	Adverb
life-sized	No	Yes	No	No
lifesize	No	Yes	No	No

As adjectives, life-sized and lifesize are synonyms defined as:

Other synonyms of life-sized include full-size, life-size.

life-sized (adjective)	lifesize (adjective)
being of the same size as an original	being of the same size as an original