meanwhile vs meantime

meanwhile and meantime both are nouns.

Word	Noun	Adjective	Verb	Adverb
meanwhile	Yes	No	No	Yes
meantime	Yes	No	No	Yes

As nouns, meanwhile and meantime are synonyms defined as:

meanwhile and meantime: the time between one event, process, or period and another

Other synonyms of meanwhile include interim, lag.

As adverbs, meanwhile and meantime are synonyms defined as:

Other synonyms of meanwhile include in the meantime.

meanwhile (noun)	meantime (noun)
the time between one event, process, or period and another	the time between one event, process, or period and another

meanwhile (adverb)	meantime (adverb)
during the intervening time	during the intervening time
at the same time but in another place