Reptile Relief, I believe, is one of many products that will kill the live mites, and thus give your snake temporary relief. However, none of the mite products will kill the eggs, so the mites will be back when the eggs hatch. In theory, you could eliminate the infestation by re-treating frequently, before the newly hatched mites get big enough to lay more eggs. However, in practice, it usually doesn't work that way, and I'm not even sure it is safe to treat the snake that often.
Provent-a-mite is different because you treat the cage rather than the snake, and it leaves a residue that will kill the mites as soon as they hatch from the eggs, so one treatment is usually enough to totally wipe them out.