of necessity vs necessarily

of necessity and necessarily both are adverbs.

Word	Noun	Adjective	Verb	Adverb
of necessity	No	No	No	Yes
necessarily	No	No	No	Yes

As adverbs, of necessity and necessarily are synonyms defined as:

of necessity and necessarily: in such a manner as could not be otherwise

Other synonyms of of necessity include inevitably, needs.

of necessity (adverb)	necessarily (adverb)
in such a manner as could not be otherwise	in an essential manner
	as a highly likely consequence
	in such a manner as could not be otherwise