Besides the physical differences, personal preference is probably the only big one here. Many people think that the males are slightly more “teddy-bear like” than the females. Neither should show any type of aggression (including dog aggression). If left unaltered, females will sometimes show a change in personality when they are coming into heat and when they are in heat. Most often, they seem to become a bit more clingy. During this time, they may not tolerate males sniffing around them or they may be extremely interested in males. If a male is left intact and used for breeding purposes and there is another intact male and a bitch in heat, the males might show some competitive aggression. However, neutered males and females will mostly differ in size (the females will be smaller) and their individual personalities. Both males and females are good with children. For your best predictor of personality, be sure to ask about and try to meet and interact with the puppy’s sire and dam. There are tests that can be done to help determine the puppy’s dominance, independence, and abilities. Be sure to ask your breeder about these. Also, socializing the puppy and general obedience training are always important.