Via and pad in PCB are two different components, and they have obvious differences in function and role.
A via is a via hole used to connect wires on different layers. They usually consist of drilled holes and pads that enable electrical connections between different layers. The hole diameter of via is generally small, and it is usually enough as long as the plate manufacturing process can be achieved.
Pad is a soldering pad, which is divided into pin pad and surface mount pad. Pin pads have solder holes and are mainly used for soldering pin components; surface mount pads have no solder holes and are mainly used for soldering surface mount components. Pad mainly plays the role of electrical connection, but also plays the role of mechanical fixation. Therefore, the aperture of the pad (when referring to the pin pad) must be large enough to pass through the pins of the component. In addition, there should be no solder resist ink on the surface of the pad, as this will affect soldering, and flux must be applied to the surface of the pad when making the board.
Generally speaking, via is mainly used to connect wires on different layers, while pad is mainly used to solder components.