Both of these products stimulate collagen, but are used in different ways. One advantage of Radiesse is that you get some fill for immediate gratification with collagen stimulation occurring later. With Sculptra, it takes several months to see the effects of collagen formation.
I use Radiesse primarily to fill lines like smile lines and often small amounts under the eyes and for cheek augmentation. I also love it to fill the back of the hands.
I use Sculptra for an overall volumizing and lifting effect. It is ideal for patients who experience hollowing as they age. This is an excellent product and worth the wait for the results it can achieve. Neither product is ideal for lips.