Well, it's true that white is just a color. It is also true that the gene pool for whites is somewhat different because the AKC considers it a disqualifying fault. So that rules out a certain kind of breeder from producing white dogs. You're also never going to see white German dogs, they will be called Berger Blanc Suisse instead and are considered a different breed. There are also people in the US who breed to the BBS standard but refer to their dogs as white GSDs. All of this could lead to the dogs having a slightly different temperament.
My dog differs from the GSD standard in many ways. She is a rescue, and I have no idea about her lineage. She is very big-boned, weighs close to 80 lbs, is less angulated than a typical GSD, and her tail carriage is a bit high, but still saber tail. Her temperament is very low-key. She is calm and gentle with everyone she meets and will only sometimes bark if someone knocks on the door. Also non-reactive to loud sounds, sudden movement, and novelty. But she is also dog-aggressive and becomes frustrated easily. We do not know whether that trait is genetic or due to lack of socialization. It is more likely the latter, I would think, since nothing in her temperament suggests she should be aggressive. She's not fearful or avoidant at all.
But yeah, bright, affectionate people pleaser. That is what I love about these dogs.