rag gourd vs sing-kwa

rag gourd and sing-kwa both are nouns.

Word	Noun	Adjective	Verb	Adverb
rag gourd	Yes	No	No	No
sing-kwa	Yes	No	No	No

As nouns, sing-kwa is a hyponym of rag gourd; that is, sing-kwa is a word with a more specific, narrower meaning than rag gourd:

rag 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
sing-kwa: loofah of Pakistan; widely cultivated throughout tropics

Other hyponyms of rag gourd include loofah, Luffa cylindrica, vegetable sponge, angled loofah, Luffa acutangula.

rag gourd (noun)	sing-kwa (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	loofah of Pakistan; widely cultivated throughout tropics