Aleris Aesthetics says Sculptra is poly-L-lactic acid, and it is the purer collagen stimulator of the two.
What Radiesse is made of
Radiesse is different in make-up. Aleris Aesthetics describes Radiesse as calcium hydroxylapatite, with microspheres suspended in a gel carrier.
So the two products start from different materials. One is poly-L-lactic acid, the other is calcium hydroxylapatite in a gel.
Safety reading for filler decisions
If you are also weighing either one against traditional hyaluronic acid filler, the FDA's dermal filler do's and don'ts is a good place to begin. A systematic review of adverse events reported from hyaluronic acid dermal filler injections adds a research view of that traditional option.
Taking it to a consultation
Ask your injector which material fits your goal and how it would be planned over your treatment course.