navel vs bellybutton

navel and bellybutton both are nouns.

Word	Noun	Adjective	Verb	Adverb
navel	Yes	No	No	No
bellybutton	Yes	No	No	No

As nouns, navel and bellybutton are synonyms defined as:

Other synonyms of navel include belly button, omphalos, omphalus, umbilicus.

navel (noun)	bellybutton (noun)
a scar where the umbilical cord was attached	a scar where the umbilical cord was attached
the center point or middle of something