topic vs blind spot

topic and blind spot both are nouns.

Word	Noun	Adjective	Verb	Adverb
topic	Yes	No	No	No
blind spot	Yes	No	No	No

As nouns, blind spot is a hyponym of topic; that is, blind spot is a word with a more specific, narrower meaning than topic:

topic: some situation or event that is thought about
blind spot: a subject about which you are ignorant or prejudiced and fail to exercise good judgment

Other hyponyms of topic include area, remit, res adjudicata, res judicata.

topic (noun)	blind spot (noun)
some situation or event that is thought about	the point where the optic nerve enters the retina; not sensitive to light
the subject matter of a conversation or discussion	a subject about which you are ignorant or prejudiced and fail to exercise good judgment