type IV allergic reaction vs delayed allergy

type IV allergic reaction and delayed allergy both are nouns.

Word	Noun	Adjective	Verb	Adverb
type IV allergic reaction	Yes	No	No	No
delayed allergy	Yes	No	No	No

As nouns, type IV allergic reaction and delayed allergy are synonyms defined as:

type IV allergic reaction and delayed allergy: an allergic reaction that becomes apparent only hours after contact

type IV allergic reaction (noun)	delayed allergy (noun)
an allergic reaction that becomes apparent only hours after contact	an allergic reaction that becomes apparent only hours after contact