bathyal district vs bathyal zone

bathyal district and bathyal zone both are nouns.

Word	Noun	Adjective	Verb	Adverb
bathyal district	Yes	No	No	No
bathyal zone	Yes	No	No	No

As nouns, bathyal district and bathyal zone are synonyms defined as:

bathyal district and bathyal zone: the steep descent of the seabed from the continental shelf to the abyssal zone

Other synonyms of bathyal district include continental slope.

bathyal district (noun)	bathyal zone (noun)
the steep descent of the seabed from the continental shelf to the abyssal zone	the steep descent of the seabed from the continental shelf to the abyssal zone