Don't expect any puppy to be completely trained until they're over 5 months old. There will still be accidents until then. . Both are the same to the person they love. I've found my boys are overall sweeter natured than my girls. Girls can get bitchy as they get older.
Boys seem to be more happy go lucky.
But I never keep two boys together if one is an Alpha male. I have one alpha that I can put with the females, but not with another male. Then I also have males that are not alpha and can run together beautifully. The same can apply to girls also. It just depends on the Yorkie's personality.