silk tree vs albizia

silk tree and albizia both are nouns.

Word	Noun	Adjective	Verb	Adverb
silk tree	Yes	No	No	No
albizia	Yes	No	No	No

As nouns, albizia is a hypernym of silk tree; that is, albizia is a word with a broader meaning than silk tree:

silk tree: attractive domed or flat-topped Asiatic tree having bipinnate leaves and flowers with long silky stamens
albizia: any of numerous trees of the genus Albizia

Other hypernyms of silk tree include albizzia.

silk tree (noun)	albizia (noun)
attractive domed or flat-topped Asiatic tree having bipinnate leaves and flowers with long silky stamens	any of numerous trees of the genus Albizia