in the beginning vs earlier

in the beginning is not an adjective while earlier is an adjective.

Word	Noun	Adjective	Verb	Adverb
in the beginning	No	No	No	Yes
earlier	No	Yes	No	Yes

As adverbs, in the beginning and earlier are synonyms defined as:

Other synonyms of in the beginning include in the first place, originally, to begin with.

in the beginning (adjective)	earlier (adjective)
	(comparative and superlative of `early') more early than; most early

in the beginning (adverb)	earlier (adverb)
with reference to the origin or beginning	earlier in time; previously
before now	comparatives of `soon' or `early'
	before now