Heaviside layer vs E layer

Heaviside layer and E layer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Heaviside layer	Yes	No	No	No
E layer	Yes	No	No	No

As nouns, Heaviside layer and E layer are synonyms defined as:

Heaviside layer and E layer: a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length

Other synonyms of Heaviside layer include E region, Kennelly-Heaviside layer.

Heaviside layer (noun)	E layer (noun)
a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length	a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length