GMT vs Greenwich Time

GMT and Greenwich Time both are nouns.

Word	Noun	Adjective	Verb	Adverb
GMT	Yes	No	No	No
Greenwich Time	Yes	No	No	No

As nouns, GMT and Greenwich Time are synonyms defined as:

GMT and Greenwich Time: the local time at the 0 meridian passing through Greenwich, England; it is the same everywhere

Other synonyms of GMT include Greenwich Mean Time, universal time, UT1, UT.

GMT (noun)	Greenwich Time (noun)
the local time at the 0 meridian passing through Greenwich, England; it is the same everywhere	the local time at the 0 meridian passing through Greenwich, England; it is the same everywhere