**Open-end wrenches** feature U-shaped jaws that enclose just one side of a fastener. They're ideal for creating high leverage but risk rounding off bolt or nut edges if not used carefully. **Box end wrenches** have fully enclosed jaws that grip fasteners from all sides, providing a secure hold but less leverage than an open-end wrench. **Combination wrenches** combine the features of both, offering an open-end on one side and a closed-end on the other, giving you versatility in tight spaces or when you need maximum leverage.