A gate valve is typically what we see for most older homes for the main shut off as well as the shut off for the water heater. A gate valve is also know as a multi-turn valve which requires several rotations to stop or resume the flow of water.
Gate valves that do not get turned on and off a lot will often get stuck in either the on of off position. An older gate valve will also tend to allow water to pass even when the valve is shut. It’s also common for a gate valve to leak after being used, especially if it’s an old valve.
A ball valve is now the preferred valve used in both residential and commercial plumbing applications. A ball valve may also be referred to as a 1/4 turn valve and a gate valve is sometimes referred to as a multi turn valve.
If a gate valve is leaking from the outside it can sometimes be stopped by tightening up the packing nut.