How do slip joint pliers differ from water pump pliers?

Water pump pliers have a more adjustable jaw design that allows them to grip larger and bulkier materials compared to slip joint pliers. This is due to their specialized design, which features a wider opening and a sturdy construction that is meant to handle the torque and leverage needed when working with larger fittings and pipes.

The design of water pump pliers, with their long handles and multiple settings for adjusting the jaw size, provides the user with better grip and leverage, making them ideal for turning and holding large components like water pipes, hoses, and fittings. Slip joint pliers, while versatile for various tasks, are not designed primarily for the same level of size adjustment or the heavy-duty applications typically handled by water pump pliers.