mastic tree vs shrub

mastic tree and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
mastic tree	Yes	No	No	No
shrub	Yes	No	No	No

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

mastic tree: an evergreen shrub of the Mediterranean region that is cultivated for its resin
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of mastic tree include bush.

mastic tree (noun)	shrub (noun)
an evergreen shrub of the Mediterranean region that is cultivated for its resin	a low woody perennial plant usually having several major stems