melon vine vs gourd vine

melon vine and gourd vine both are nouns.

Word	Noun	Adjective	Verb	Adverb
melon vine	Yes	No	No	No
gourd vine	Yes	No	No	No

As nouns, gourd vine is a hypernym of melon vine; that is, gourd vine is a word with a broader meaning than melon vine:

melon vine: any of various fruit of cucurbitaceous vines including: muskmelons, watermelons, cantaloupes, cucumbers
gourd vine: any vine of the family Cucurbitaceae that bears fruits with hard rinds

Other hypernyms of melon vine include gourd.

melon vine (noun)	gourd vine (noun)
any of various fruit of cucurbitaceous vines including: muskmelons, watermelons, cantaloupes, cucumbers	any vine of the family Cucurbitaceae that bears fruits with hard rinds