epic vs larger-than-life

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

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

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

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

Other synonyms of epic include heroic.

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

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