newbie vs fledgling

newbie and fledgling both are nouns.

Word	Noun	Adjective	Verb	Adverb
newbie	Yes	No	No	No
fledgling	Yes	Yes	No	No

As nouns, newbie and fledgling are synonyms defined as:

Other synonyms of newbie include entrant, fledgeling, freshman, neophyte, newcomer, starter.

newbie (noun)	fledgling (noun)
any new participant in some activity	young bird that has just fledged or become capable of flying
	any new participant in some activity

newbie (adjective)	fledgling (adjective)
	(of a young bird) having acquired its flight feathers
	young and inexperienced