silk cotton vs vegetable silk

silk cotton and vegetable silk both are nouns.

Word	Noun	Adjective	Verb	Adverb
silk cotton	Yes	No	No	No
vegetable silk	Yes	No	No	No

As nouns, silk cotton and vegetable silk are synonyms defined as:

silk cotton and vegetable silk: a plant fiber from the kapok tree; used for stuffing and insulation

Other synonyms of silk cotton include kapok.

silk cotton (noun)	vegetable silk (noun)
a plant fiber from the kapok tree; used for stuffing and insulation	a plant fiber from the kapok tree; used for stuffing and insulation