Ampere's Law is the more fundamental law. However, there isn't much you can do with it alone. You can, for example, use it to deduce the magnetic field of an infinite wire but it is generally used in conjunction with the other three Maxwell's Equations to solve for a specific problem. The Biot-Savart Law is a specific application of Ampere's Law and other Maxwell Equation's to describe the magnetic field due to a DC current source. It is only valid for magnetostatics. The Jefimenko equations are the equivalent to the Biot-Savart but valid for all situations.