robot vs automaton

robot and automaton both are nouns.

Word	Noun	Adjective	Verb	Adverb
robot	Yes	No	No	No
automaton	Yes	No	No	No

As nouns, robot and automaton are synonyms defined as:

Other synonyms of robot include golem.

robot (noun)	automaton (noun)
a mechanism that can move automatically	a mechanism that can move automatically
	a machine that operates on its own without the need for human control
	someone who acts or responds in a mechanical or apathetic way