I have had many years of experience with all of the different fillers. When comparing Juvederm and Restylane - Juvederm lasts much longer in most parts of the face. In the lips, neither lasts very long.
Keep in mind that results vary from patient to patient, but usually I see:
Juvederm - 6-10 months
Restylane - 5-7 months
Both last 3-5 months in the lips