tree heath vs true heath

tree heath and true heath both are nouns.

Word	Noun	Adjective	Verb	Adverb
tree heath	Yes	No	No	No
true heath	Yes	No	No	No

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

tree heath: evergreen treelike Mediterranean shrub having fragrant white flowers in large terminal panicles and hard woody roots used to make tobacco pipes
true heath: any plant of the genus Erica

Other hypernyms of tree heath include erica.

tree heath (noun)	true heath (noun)
evergreen treelike Mediterranean shrub having fragrant white flowers in large terminal panicles and hard woody roots used to make tobacco pipes	any plant of the genus Erica
gaunt Tasmanian evergreen shrubby tree with slender tapering leaves 3 to 5 feet long