blackthorn vs hawthorn

blackthorn and hawthorn both are nouns.

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

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

blackthorn: erect and almost thornless American hawthorn with somewhat pear-shaped berries
hawthorn: a spring-flowering shrub or small tree of the genus Crataegus

Other hypernyms of blackthorn include haw.

blackthorn (noun)	hawthorn (noun)
erect and almost thornless American hawthorn with somewhat pear-shaped berries	a spring-flowering shrub or small tree of the genus Crataegus
a thorny Eurasian bush with plumlike fruits