earliest vs earlier

earliest and earlier both are adjectives.

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

As adjectives, earliest and earlier are synonyms defined as:

earliest and earlier: (comparative and superlative of `early') more early than; most early

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

earliest (adverb)	earlier (adverb)
with the least delay	earlier in time; previously
	comparatives of `soon' or `early'
	before now