berm vs hard shoulder

berm and hard shoulder both are nouns.

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

As nouns, hard shoulder is a hyponym of berm; that is, hard shoulder is a word with a more specific, narrower meaning than berm:

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

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