anxiety vs overanxiety

anxiety and overanxiety both are nouns.

Word	Noun	Adjective	Verb	Adverb
anxiety	Yes	No	No	No
overanxiety	Yes	No	No	No

As nouns, overanxiety is a hyponym of anxiety; that is, overanxiety is a word with a more specific, narrower meaning than anxiety:

anxiety: (psychiatry) a relatively permanent state of worry and nervousness occurring in a variety of mental disorders, usually accompanied by compulsive behavior or attacks of panic
overanxiety: excessive anxiety

Other hyponyms of anxiety include castration anxiety, hypochondria, hypochondriasis, panic, scare, social anxiety.

anxiety (noun)	overanxiety (noun)
a vague unpleasant emotion that is experienced in anticipation of some (usually ill-defined) misfortune	excessive anxiety
(psychiatry) a relatively permanent state of worry and nervousness occurring in a variety of mental disorders, usually accompanied by compulsive behavior or attacks of panic