annoyance vs irritant

annoyance and irritant both are nouns.

Word	Noun	Adjective	Verb	Adverb
annoyance	Yes	No	No	No
irritant	Yes	No	No	No

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

annoyance: something or someone that causes trouble; a source of unhappiness
irritant: something that causes irritation and annoyance

Other hyponyms of annoyance include nuisance, thorn, plague.

annoyance (noun)	irritant (noun)
the act of troubling or annoying someone	something that causes irritation and annoyance
something or someone that causes trouble; a source of unhappiness
anger produced by some annoying irritation
an unpleasant person who is annoying or exasperating
the psychological state of being irritated or annoyed