region vs E region

region and E region both are nouns.

Word	Noun	Adjective	Verb	Adverb
region	Yes	No	No	No
E region	Yes	No	No	No

region (noun)	E region (noun)
a part of an animal that has a special function or is supplied by a given artery or nerve	a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length
a knowledge domain that you are interested in or are communicating about
the extended spatial location of something
a large indefinite location on the surface of the Earth
the approximate amount of something (usually used prepositionally as in `in the region of')