obsession vs irrational motive

obsession and irrational motive both are nouns.

Word	Noun	Adjective	Verb	Adverb
obsession	Yes	No	No	No
irrational motive	Yes	No	No	No

As nouns, irrational motive is a hypernym of obsession; that is, irrational motive is a word with a broader meaning than obsession:

obsession: an irrational motive for performing trivial or repetitive actions, even against your will
irrational motive: a motivation that is inconsistent with reason or logic

obsession (noun)	irrational motive (noun)
an unhealthy and compulsive preoccupation with something or someone	a motivation that is inconsistent with reason or logic
an irrational motive for performing trivial or repetitive actions, even against your will