What filler to choose - Hi my question is, what's the difference between Restylane and Restylane Silk?

They are both Hyaluronic Acid Fillers but, Restylane Silk is slightly thinner than Restylane. This is why Restylane Silk is preferred in the under-eye area. Depending on the volume deficit, Restylane might be indicated as well.  
 

Hello,Good question.  Most injectors that perform "tear trough" treatments (under the eyes) prefer Restylane as this is a smooth gel that is safe, predictable, and offers a solid duration of 9 to 12 months or longer in this area.  Although not FDA approved for tear troughs, this is the most common filler used for this service.  Restylane SILK is a much thinner product which is ideal for fine lines or treatment of the mouth/lips.  It's not clear why your injector would prefer SILK given that Restylane is the better choice as well as a lower price tag.  

Hello, 

Thank you for your question. Restylane Silk is made with a smaller molecule, it tends to look better under the eyes because its softer than the regular Restylane. However both can be used under the eyes. Good luck!

Regular Restylane is thicker and more likely to cause bumps or nodules when used in thin skin areas like the lower lids vs #restylane silk which is thinner and less likely to cause these problems.Restylane® Silk has recently been approved by the FDA for release in the United States. It’s the first and only approved product specifically designed for smoothing wrinkles and lines around the mouth, as well as replacing lost volume. 

Both are safe FDA approved
hyaluronic acid fillers. Restylane Silk can be injected in a more
superficial dermal position. Restylane is a soft tissue filler injected below the dermis for fine upper lip wrinkles. I
would consider using a hyaluronic acid filler like Restylane for the tear
trough correction, which will not cause

significant swelling and can last for over a year. This should be done in the
hands of a Board Certified
Plastic Surgeon or Dermatologist.