pigeonhole vs sort out

pigeonhole is a noun but sort out is not a noun.

Word	Noun	Adjective	Verb	Adverb
pigeonhole	Yes	No	Yes	No
sort out	No	No	Yes	No

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

Other hypernyms of pigeonhole include assort, class, classify, separate, sort.

pigeonhole (noun)	sort out (noun)
a small compartment
a specific (often simplistic) category

pigeonhole (verb)	sort out (verb)
treat or classify according to a mental stereotype	arrange or order by classes or categories
place into a small compartment	make free from confusion or ambiguity; make clear
	punish in order to gain control or enforce obedience