thistledown vs pappus

thistledown and pappus both are nouns.

Word	Noun	Adjective	Verb	Adverb
thistledown	Yes	No	No	No
pappus	Yes	No	No	No

As nouns, pappus is a hypernym of thistledown; that is, pappus is a word with a broader meaning than thistledown:

thistledown: pappus of a thistle consisting of silky featherlike hairs attached to the seed-like fruit of a thistle
pappus: calyx composed of scales or bristles or featherlike hairs in plants of the Compositae such as thistles and dandelions

thistledown (noun)	pappus (noun)
pappus of a thistle consisting of silky featherlike hairs attached to the seed-like fruit of a thistle	calyx composed of scales or bristles or featherlike hairs in plants of the Compositae such as thistles and dandelions