Jazz: 1.5" nut width

Precision: 1.625" nut width, slightly thicker profile (back to front) as well

Assuming they are the standard versions of the respective basses.
Quote by MetalUpTheAss
Sounds to me like an excuse.

"Honey, I've got to buy a new bass! This diamond is made of a dead guy! I made him a promise!"

Most Bitter/Cynical member of the Bass Militia. PM DinkyDaisy to join.
in general, the jazz has a slimmer neck. it'll be more comfortable on smaller hands. the p-bass neck is pretty much bigger, and subsequently heavier. players like billy sheehan prefer the bigger heavier neck, saying it has a better feel tone and sustain.

to be fair, his fingers are long as hell. me personally i prefer the jazz necks as my hands are pretty small.