Are white mice smarter than other mice or are all mice just the same?

Both are as smart. Just like blonde and non-blonde people. It's just a myth that I had never heard before.

http://www.theatlantic.com/technology/archive/2014/10/rats-arent-smarter-than-mice-and-that-actually-matters/381430/

Mice are actually very variable in terms of intelligence and personality. I used to breed mice and noticed differences in individuals which were siblings or cousins. Some were quick to learn, others slow, some were highly aggressive, others more placid. This is also true for many domestic animals such as horses and dogs. This has to be born in mind when performing intelligence tests on any mammals, and a large sample is needed for meaningful results.