It is not a dumb question at all. We had a fun contest not too long ago to see if we knew the difference between the 2. (yorkie v silky) And to be honest most of us could not tell the difference. From my understanding the Silky is a bit larger, longer body and a bit of a longer snout. Still every beautiful and looks like a yorkie to me. Here is a good site that I found. It may answer some question you may have about the difference.
http://www.agt.net/public/silkyd/breeddifferences.htm