each vs to each one

each is an adjective but to each one is not an adjective.

Word	Noun	Adjective	Verb	Adverb
each	No	Yes	No	Yes
to each one	No	No	No	Yes

As adverbs, each and to each one are synonyms defined as:

each and to each one: to or from every one of two or more (considered individually)

Other synonyms of each include apiece, for each one, from each one.

each (adjective)	to each one (adjective)
(used of count nouns) every one considered individually; quantifier, singular, universal pronoun; quantifier, singular, universal

each (adverb)	to each one (adverb)
to or from every one of two or more (considered individually)	to or from every one of two or more (considered individually)