rub vs irritate

rub is a noun but irritate is not a noun.

Word	Noun	Adjective	Verb	Adverb
rub	Yes	No	Yes	No
irritate	No	No	Yes	No

As verbs, irritate is a hypernym of rub; that is, irritate is a word with a broader meaning than rub:

rub (noun)	irritate (noun)
the act of rubbing or wiping
an unforeseen obstacle

rub (verb)	irritate (verb)
move over something with pressure	excite to an abnormal condition, or chafe or inflame
cause friction	excite to some characteristic action or condition, such as motion, contraction, or nervous impulse, by the application of a stimulus
scrape or rub as if to relieve itching	cause annoyance in; disturb, especially by minor irritations