lunar excursion module vs lunar module

lunar excursion module and lunar module both are nouns.

Word	Noun	Adjective	Verb	Adverb
lunar excursion module	Yes	No	No	No
lunar module	Yes	No	No	No

As nouns, lunar excursion module and lunar module are synonyms defined as:

lunar excursion module and lunar module: a spacecraft that carries astronauts from the command module to the surface of the moon and back

Other synonyms of lunar excursion module include LEM.

lunar excursion module (noun)	lunar module (noun)
a spacecraft that carries astronauts from the command module to the surface of the moon and back	a spacecraft that carries astronauts from the command module to the surface of the moon and back