lunar excursion module vs LEM

lunar excursion module and LEM both are nouns.

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

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

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

Other synonyms of lunar excursion module include lunar module.

lunar excursion module (noun)	LEM (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