belle de nuit vs morning glory

belle de nuit and morning glory both are nouns.

Word	Noun	Adjective	Verb	Adverb
belle de nuit	Yes	No	No	No
morning glory	Yes	No	No	No

As nouns, morning glory is a hypernym of belle de nuit; that is, morning glory is a word with a broader meaning than belle de nuit:

belle de nuit: pantropical climber having white fragrant nocturnal flowers
morning glory: any of various twining vines having funnel-shaped flowers that close late in the day

belle de nuit (noun)	morning glory (noun)
pantropical climber having white fragrant nocturnal flowers	any of various twining vines having funnel-shaped flowers that close late in the day