cardiac pacemaker vs sinoatrial node

cardiac pacemaker and sinoatrial node both are nouns.

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

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

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

Other synonyms of cardiac pacemaker include pacemaker, SA node.

cardiac pacemaker (noun)	sinoatrial node (noun)
a specialized bit of heart tissue that controls the heartbeat	a specialized bit of heart tissue that controls the heartbeat