life story vs biography

life story and biography both are nouns.

Word	Noun	Adjective	Verb	Adverb
life story	Yes	No	No	No
biography	Yes	No	No	No

As nouns, life story and biography are synonyms defined as:

life story and biography: an account of the series of events making up a person's life

Other synonyms of life story include life, life history.

life story (noun)	biography (noun)
an account of the series of events making up a person's life	an account of the series of events making up a person's life