hard shoulder vs berm

hard shoulder and berm both are nouns.

Word	Noun	Adjective	Verb	Adverb
hard shoulder	Yes	No	No	No
berm	Yes	No	No	No

As nouns, berm is a hypernym of hard shoulder; that is, berm is a word with a broader meaning than hard shoulder:

hard shoulder: a paved strip beside a motorway (for stopping in emergencies)
berm: a narrow edge of land (usually unpaved) along the side of a road

Other hypernyms of hard shoulder include shoulder.

hard shoulder (noun)	berm (noun)
a paved strip beside a motorway (for stopping in emergencies)	a narrow edge of land (usually unpaved) along the side of a road
	a narrow ledge or shelf typically at the top or bottom of a slope