before vs earlier

before is not an adjective while earlier is an adjective.

Word	Noun	Adjective	Verb	Adverb
before	No	No	No	Yes
earlier	No	Yes	No	Yes

As adverbs, before and earlier are synonyms defined as:

before (adjective)	earlier (adjective)
	(comparative and superlative of `early') more early than; most early

before (adverb)	earlier (adverb)
at or in the front	earlier in time; previously
earlier in time; previously	comparatives of `soon' or `early'
	before now