skylark vs run around

skylark is a noun but run around is not a noun.

Word	Noun	Adjective	Verb	Adverb
skylark	Yes	No	Yes	No
run around	No	No	Yes	No

As verbs, skylark and run around are synonyms defined as:

Other synonyms of skylark include cavort, disport, frisk, frolic, gambol, lark, lark about, rollick, romp, sport.

skylark (noun)	run around (noun)
brown-speckled European lark noted for singing while hovering at a great height

skylark (verb)	run around (verb)
play boisterously	play boisterously