What's the difference between Juvederm ultra 2, 3, 4 and Juvederm smile?

Are the end results different, do they last longer etc? I've had juvederm ultra 3 use in my lips one before and the results were satisfactory as I asked for natural looking, fuller lips. However, 6 months later and my lips are almost back to their natural form and it's time for me to get some more injections but this time round I think I might want something a bit more noticeable but still nothing too dramatic. I don't know whether I should stick to ultra 3 or try one of the other juvederm fillers?

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