cardiac pacemaker vs pacemaker

cardiac pacemaker and pacemaker both are nouns.

Word	Noun	Adjective	Verb	Adverb
cardiac pacemaker	Yes	No	No	No
pacemaker	Yes	No	No	No

As nouns, cardiac pacemaker and pacemaker are synonyms defined as:

cardiac pacemaker and pacemaker: a specialized bit of heart tissue that controls the heartbeat

Other synonyms of cardiac pacemaker include SA node, sinoatrial node.

cardiac pacemaker (noun)	pacemaker (noun)
a specialized bit of heart tissue that controls the heartbeat	a horse used to set the pace in racing
	an implanted electronic device that takes over the function of the natural cardiac pacemaker
	a specialized bit of heart tissue that controls the heartbeat
	a leading instance in its field