sinoatrial node vs cardiac pacemaker

sinoatrial node and cardiac pacemaker both are nouns.

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

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

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

Other synonyms of sinoatrial node include pacemaker, SA node.

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