mechanical vs automatic

mechanical is not a noun while automatic is a noun.

Word	Noun	Adjective	Verb	Adverb
mechanical	No	Yes	No	No
automatic	Yes	Yes	No	No

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

mechanical (adjective)	automatic (adjective)
using (or as if using) mechanisms or tools or devices	operating with minimal human intervention; independent of external control
relating to or governed by or in accordance with mechanics	without volition or conscious control
relating to or concerned with machinery or tools	resembling the unthinking functioning of a machine