blackthorn vs shrub

blackthorn and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
blackthorn	Yes	No	No	No
shrub	Yes	No	No	No

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

Other hypernyms of blackthorn include bush.

blackthorn (noun)	shrub (noun)
erect and almost thornless American hawthorn with somewhat pear-shaped berries	a low woody perennial plant usually having several major stems
a thorny Eurasian bush with plumlike fruits