atopy vs type I allergic reaction

atopy and type I allergic reaction both are nouns.

Word	Noun	Adjective	Verb	Adverb
atopy	Yes	No	No	No
type I allergic reaction	Yes	No	No	No

As nouns, atopy and type I allergic reaction are synonyms defined as:

atopy and type I allergic reaction: an allergic reaction that becomes apparent in a sensitized person only minutes after contact

Other synonyms of atopy include atopic allergy, immediate allergy.

atopy (noun)	type I allergic reaction (noun)
an allergic reaction that becomes apparent in a sensitized person only minutes after contact	an allergic reaction that becomes apparent in a sensitized person only minutes after contact