lark vs run around

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

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

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

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

lark (noun)	run around (noun)
any carefree episode
any of numerous predominantly Old World birds noted for their singing
a songbird that lives mainly on the ground in open country; has streaky brown plumage
North American songbirds having a yellow breast

lark (verb)	run around (verb)
play boisterously	play boisterously