As others have said, the classic question, which for me can be answered:
The neck on a Jazz is slimmer. This could make it an easier bass to learn on.
Precision has one pickup, and a very meaty/full powerful sound.
Jazz has two pickups, a more refined sound, and more variety of sounds due to having two pickups.
The Jazz can get fairly near the sound of the Precision, the Precision can’t get hear the sound of the Jazz.
And finally, both of those CVS are basses I’d have been happy to have as my first bass, and similarly as others have said, go with your gut feeling and get the one that you’ve thought about and really wanted.