sponge gourd vs loofah

sponge gourd and loofah both are nouns.

Word	Noun	Adjective	Verb	Adverb
sponge gourd	Yes	No	No	No
loofah	Yes	No	No	No

As nouns, loofah is a hyponym of sponge gourd; that is, loofah is a word with a more specific, narrower meaning than sponge gourd:

sponge gourd: any of several tropical annual climbers having large yellow flowers and edible young fruits; grown commercially for the mature fruit's dried fibrous interior that is used as a sponge
loofah: the loofah climber that has cylindrical fruit

Other hyponyms of sponge gourd include Luffa cylindrica, vegetable sponge, angled loofah, Luffa acutangula, sing-kwa.

sponge gourd (noun)	loofah (noun)
any of several tropical annual climbers having large yellow flowers and edible young fruits; grown commercially for the mature fruit's dried fibrous interior that is used as a sponge	the loofah climber that has cylindrical fruit
	the dried fibrous part of the fruit of a plant of the genus Luffa; used as a washing sponge or strainer