Loretta....I have a biewer and yorkies...no parti at my house unless you want to perform a little experiment and send me one.
As far as structure...Reggie is smaller than my yorkies. The biewer standard for size is the same as the yorkshire terrier.
Temperament wise...Reggie is much gentler. He is not as hyper. My yorkies are jumping beans...Reggie does not jump. He has never tried to jump onto any piece of furniture...he asks you to pick him up. He is very inquistive. He'll investigate the source of the noise...while Ramsey and Reese tend to shy away from the "unknown". Reggie is very smart. Like...he has figured out he can never catch Reese...so he will hide from Reese...then jump out at him when Reese runs by. Reese will have a toy that Reggie wants....Reggie will go get something else...shove it in Reese's face...Reese takes the bait and Reggie gets the item he wanted in the first place.
He gets along well with his yorkie siblings. Very much into rough housing.
I have never seen a biewer with a mis-matched face. I've seen some with a white blaze or muzzle and some without but not white on one side and black on the other.
Some differences I see...I ponder if it is really a difference in the breed or a difference in personality. Both of my yorkies have distinct personalities.
I'm sure the biewer breeders have loads of info to share with you.
PS If you need a nudge...get a biewer.