vegetable silk vs silk cotton

vegetable silk and silk cotton both are nouns.

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

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

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

Other synonyms of vegetable silk include kapok.

vegetable silk (noun)	silk cotton (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