lark vs skylark

lark and skylark both are nouns.

Word	Noun	Adjective	Verb	Adverb
lark	Yes	No	Yes	No
skylark	Yes	No	Yes	No

As nouns, skylark is a hyponym of lark; that is, skylark is a word with a more specific, narrower meaning than lark:

lark: any of numerous predominantly Old World birds noted for their singing
skylark: brown-speckled European lark noted for singing while hovering at a great height

Other hyponyms of lark include Alauda arvensis.

As verbs, lark and skylark are synonyms defined as:

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

lark (noun)	skylark (noun)
any carefree episode	brown-speckled European lark noted for singing while hovering at a great height
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)	skylark (verb)
play boisterously	play boisterously