velvet flower vs amaranth

velvet flower and amaranth both are nouns.

Word	Noun	Adjective	Verb	Adverb
velvet flower	Yes	No	No	No
amaranth	Yes	No	No	No

As nouns, amaranth is a hypernym of velvet flower; that is, amaranth is a word with a broader meaning than velvet flower:

velvet flower: young leaves widely used as leaf vegetables; seeds used as cereal
amaranth: any of various plants of the genus Amaranthus having dense plumes of green or red flowers; often cultivated for food

velvet flower (noun)	amaranth (noun)
young leaves widely used as leaf vegetables; seeds used as cereal	any of various plants of the genus Amaranthus having dense plumes of green or red flowers; often cultivated for food
	seed of amaranth plants used as a native cereal in Central and South America