segregate vs single out

segregate is a noun but single out is not a noun.

Word	Noun	Adjective	Verb	Adverb
segregate	Yes	No	Yes	No
single out	No	No	Yes	No

As verbs, single out is a hypernym of segregate; that is, single out is a word with a broader meaning than segregate:

segregate: separate by race or religion; practice a policy of racial segregation
single out: treat differently on the basis of sex or race

Other hypernyms of segregate include discriminate, separate.

segregate (noun)	single out (noun)
someone who is or has been segregated

segregate (verb)	single out (verb)
separate or isolate (one thing) from another and place in a group apart from others	select from a group
divide from the main body or mass and collect	treat differently on the basis of sex or race
separate by race or religion; practice a policy of racial segregation