On opening the gate valve, the flow path is enlarged in a highly nonlinear manner with respect to percent of opening. Fow rate in gate valve does not change evenly with stem travel. They are designed to be fully opened or closed. When fully open, it has no obstruction in the flow path, resulting in very low friction loss. And they are should never be used for regulating flow, unless they are specifically designed for that purpose.
Check valve is a mechanical device, which allows fluid or gas to flow through it in only one direction. It's simple, small and do not has valve handle or stem. It can be divided into swing and spring check valve. They can be designed for and can be specified for a specific cracking pressure. They are often used in many fluid systems and in many other industrial processes. These valves often look like small cylinders attached to the pump head on the inlet and outlet lines.