annually vs each year

annually and each year both are adverbs.

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

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

Other synonyms of annually include every year, yearly.

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

annually and each year: by the year; every year (usually with reference to a sum of money paid or received)

Other synonyms of annually include p.a., per annum, per year.

annually (adverb)	each year (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)	by the year; every year (usually with reference to a sum of money paid or received)