This is education, not advice
The information here is written for the general reader and does not replace a personal medical consultation. It cannot tell you which material is appropriate for your face, how your tissue would respond to a collagen stimulator, or whether either is safe for you.
No outcome is guaranteed
No treatment can be guaranteed. How much collagen is laid down, how evenly it is distributed, how long a filler persists and how the skin responds all vary between individuals. A clinician who promises a specific result before examining you is describing something other than medicine.
One of the two cannot be dissolved
A hyaluronic acid filler can usually be broken down with an enzyme. A collagen stimulator cannot, and a result that is wrong has to be managed over months rather than reversed. That is the most important practical difference between the two and it is stated here before any benefit is described.
Nodules are a recognised complication
Small firm areas under the skin are the characteristic complication of collagen stimulators. They are more likely with superficial placement or inadequately prepared material, and they are managed rather than dissolved. No injector can promise that they will not occur.