Spanish heath vs true heath

Spanish heath and true heath both are nouns.

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

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

Spanish heath: erect dense shrub native to western Iberian peninsula having profuse white or pink flowers; naturalized in southwestern England
true heath: any plant of the genus Erica

Other hypernyms of Spanish heath include erica.

Spanish heath (noun)	true heath (noun)
erect dense shrub native to western Iberian peninsula having profuse white or pink flowers; naturalized in southwestern England	any plant of the genus Erica