limbic brain vs limbic system

limbic brain and limbic system both are nouns.

Word	Noun	Adjective	Verb	Adverb
limbic brain	Yes	No	No	No
limbic system	Yes	No	No	No

As nouns, limbic brain and limbic system are synonyms defined as:

limbic brain and limbic system: a system of functionally related neural structures in the brain that are involved in emotional behavior

Other synonyms of limbic brain include visceral brain.

limbic brain (noun)	limbic system (noun)
a system of functionally related neural structures in the brain that are involved in emotional behavior	a system of functionally related neural structures in the brain that are involved in emotional behavior