machine rifle vs automatic

machine rifle and automatic both are nouns.

Word	Noun	Adjective	Verb	Adverb
machine rifle	Yes	No	No	No
automatic	Yes	Yes	No	No

As nouns, machine rifle and automatic are synonyms defined as:

machine rifle and automatic: self-loading rifle capable of automatic fire

Other synonyms of machine rifle include automatic rifle.

machine rifle (noun)	automatic (noun)
self-loading rifle capable of automatic fire	self-loading rifle capable of automatic fire
	a pistol that will keep firing until the ammunition is gone or the trigger is released

machine rifle (adjective)	automatic (adjective)
	operating with minimal human intervention; independent of external control
	without volition or conscious control
	resembling the unthinking functioning of a machine