Hello!! While NSDTR and brittany spaniels are both gundogs, their purposes are pretty different (retrieving vs flushing, respectively) so I assume their personalities would be pretty different. Retrievers tend to be more biddable and work closer to their handlers, whereas flushing or pointing dogs tend to more independent and happy to go off and work on their own. That said, their personalities will probably overlap quite a bit (small, loud, high energy, good off switch in the house, soft temperaments, driven).
Followers who own one or the other, care to chime in with your experiences?