larger-than-life vs epic

larger-than-life is not a noun while epic is a noun.

Word	Noun	Adjective	Verb	Adverb
larger-than-life	No	Yes	No	No
epic	Yes	Yes	No	No

As adjectives, larger-than-life and epic are synonyms defined as:

larger-than-life and epic: very imposing or impressive; surpassing the ordinary (especially in size or scale)

Other synonyms of larger-than-life include heroic.

larger-than-life (noun)	epic (noun)
	a long narrative poem telling of a hero's deeds

larger-than-life (adjective)	epic (adjective)
very imposing or impressive; surpassing the ordinary (especially in size or scale)	constituting or having to do with or suggestive of a literary epic
	very imposing or impressive; surpassing the ordinary (especially in size or scale)