each year vs yearly

each year is not a noun while yearly is a noun.

Word	Noun	Adjective	Verb	Adverb
each year	No	No	No	Yes
yearly	Yes	Yes	No	Yes

As adverbs, each year and yearly are synonyms defined as:

Other synonyms of each year include annually, every year.

each year (noun)	yearly (noun)
	a reference book that is published regularly once every year

each year (adjective)	yearly (adjective)
	occurring or payable every year

each year (adverb)	yearly (adverb)
without missing a year	without missing a year
by the year; every year (usually with reference to a sum of money paid or received)