time zone vs geographical zone

time zone and geographical zone both are nouns.

Word	Noun	Adjective	Verb	Adverb
time zone	Yes	No	No	No
geographical zone	Yes	No	No	No

As nouns, geographical zone is a hypernym of time zone; that is, geographical zone is a word with a broader meaning than time zone:

time zone: any of the 24 regions of the globe (loosely divided by longitude) throughout which the same standard time is used
geographical zone: any of the regions of the surface of the Earth loosely divided according to latitude or longitude

Other hypernyms of time zone include zone.

time zone (noun)	geographical zone (noun)
any of the 24 regions of the globe (loosely divided by longitude) throughout which the same standard time is used	any of the regions of the surface of the Earth loosely divided according to latitude or longitude