pacemaker vs SA node

pacemaker and SA node both are nouns.

Word	Noun	Adjective	Verb	Adverb
pacemaker	Yes	No	No	No
SA node	Yes	No	No	No

As nouns, pacemaker and SA node are synonyms defined as:

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

Other synonyms of pacemaker include cardiac pacemaker, sinoatrial node.

pacemaker (noun)	SA node (noun)
a horse used to set the pace in racing	a specialized bit of heart tissue that controls the heartbeat
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