automatic vs machine rifle

automatic and machine rifle both are nouns.

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

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

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

Other synonyms of automatic include automatic rifle.

automatic (noun)	machine rifle (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

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