Live is our production environment. All orders that get created through the live API/manual order form will be charged and routed through to labs as you’d expect.
Sandbox does not charge and does not fulfill any orders. Its primary purpose is for merchants to come and try out the API/manual order form in a semi-real way without risk of being charged or accidentally ordering something.
We keep Sandbox as up-to-date as Live, so you’ll always see the newest features on both.