in the first place vs earlier

in the first place is not an adjective while earlier is an adjective.

Word	Noun	Adjective	Verb	Adverb
in the first place	No	No	No	Yes
earlier	No	Yes	No	Yes

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

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

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

in the first place (adverb)	earlier (adverb)
of primary import	earlier in time; previously
before now	comparatives of `soon' or `early'
	before now