single out vs tell apart

single out and tell apart both are verbs.

Word	Noun	Adjective	Verb	Adverb
single out	No	No	Yes	No
tell apart	No	No	Yes	No

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

Other hypernyms of single out include differentiate, distinguish, secern, secernate, separate, severalise, severalize, tell.

single out (verb)	tell apart (verb)
select from a group	mark as different
treat differently on the basis of sex or race	detect with the senses