I thought I would try to answer your question since no one else has
I've only had 1 Yorkie and he's only 8 mos old but as far as I know and from things I've learned on here, there really is no way to tell either of these from a puppy.
All Yorkie puppies are born black and tan and have a more cottony coat. It's almost impossible to tell if the hair will stay cottony or turn silky or if it will stay black and tan or turn blue/gray/silver and tan/gold.
Like I've heard someone say on here.... Yorkies are like a box of chocolates, you never know what you are going to get