selective amnesia vs blackout

selective amnesia and blackout both are nouns.

Word	Noun	Adjective	Verb	Adverb
selective amnesia	Yes	No	No	No
blackout	Yes	No	No	No

As nouns, blackout is a hypernym of selective amnesia; that is, blackout is a word with a broader meaning than selective amnesia:

selective amnesia: amnesia about particular events that is very convenient for the person who cannot remember
blackout: partial or total loss of memory

Other hypernyms of selective amnesia include amnesia, memory loss.

selective amnesia (noun)	blackout (noun)
amnesia about particular events that is very convenient for the person who cannot remember	a momentary loss of consciousness
	partial or total loss of memory
	the failure of electric power for a general region
	darkness resulting from the extinction of lights (as in a city invisible to enemy aircraft)
	a suspension of radio or tv broadcasting