sinoatrial node vs SA node

sinoatrial node and SA node both are nouns.

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

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

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

Other synonyms of sinoatrial node include cardiac pacemaker, pacemaker.

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