life-time vs lifetime

life-time and lifetime both are nouns.

Word	Noun	Adjective	Verb	Adverb
life-time	Yes	No	No	No
lifetime	Yes	No	No	No

As nouns, life-time and lifetime are synonyms defined as:

life-time and lifetime: the period during which something is functional (as between birth and death)

Other synonyms of life-time include life, lifespan.

life-time (noun)	lifetime (noun)
the period during which something is functional (as between birth and death)	the period during which something is functional (as between birth and death)