dwarf chestnut vs chestnut tree

dwarf chestnut and chestnut tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
dwarf chestnut	Yes	No	No	No
chestnut tree	Yes	No	No	No

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

dwarf chestnut: shrubby chestnut tree of southeastern United States having small edible nuts
chestnut tree: any of several attractive deciduous trees yellow-brown in autumn; yield a hard wood and edible nuts in a prickly bur

Other hypernyms of dwarf chestnut include chestnut.

dwarf chestnut (noun)	chestnut tree (noun)
shrubby chestnut tree of southeastern United States having small edible nuts	any of several attractive deciduous trees yellow-brown in autumn; yield a hard wood and edible nuts in a prickly bur