twilight zone vs sea bottom

twilight zone and sea bottom both are nouns.

Word	Noun	Adjective	Verb	Adverb
twilight zone	Yes	No	No	No
sea bottom	Yes	No	No	No

As nouns, sea bottom is a hypernym of twilight zone; that is, sea bottom is a word with a broader meaning than twilight zone:

Other hypernyms of twilight zone include Davy Jones's locker, Davy Jones, ocean bottom, ocean floor, sea floor, seabed.

twilight zone (noun)	sea bottom (noun)
the ambiguous region between two categories or states or conditions (usually containing some features of both)	the bottom of a sea or ocean
the lowest level of the ocean to which light can reach