Comparing apples and oranges. Online pharmacy handles already prepared medication and will usually bill your insurance company. Compounding pharmacies compound products that are not available or sometimes doses that are not commercially available. They usually will not bill your insurance company. You pay the pharmacy and submit your claim to the insurance company. Sometimes you can be reimbursed for the script but usually because of some of the screwy rules the insurance companies have when it comes to compounded prescriptions it will be excluded and not reimbursed.