To me, there is a big difference between yorkies and silkies. A bigger yorkie does not look like a silky unless it was bred with a silky. Silkies have have wedge shaped head, longer muzzle flatter skull, ears stand erect on the top of the head, they are longer in body than tall at the shoulders and are sturdy and well muscled.
Yorkies on the otherhand have heavier coats, shorter muzzles and a dome shaped head, ears are erect but tend to flare to the sit a bit and the ear base is larger than a silky, they are as tall as they are long like a square or box, their features are overall more daintefied and fragile than the sturdy muscular silky. Just looking at the face alone you should be able to tell the difference.
So to say a yorkie looks like a silky just because of it size is not fair. Yorkies use to be alot bigger and now the size is 7 pounds or under. Nonetheless, their are still yorkies out there that have genes for bigger yorkies, I think we will always have that due to puppy mills and such.
I am not trying to be critize, I just think there is a big difference between yorkies and silkies other than just weight.
