Box end design that allows more contact with the fastener's sides than the 12-pt.
Style and prevents rounding the fastener's corners.
Double-end wrenches have a different SAE (inch) size on each end for use on two different size fasteners.
The ratcheting box ends have a gear mechanism that allows the wrench to rotate freely in one direction without removing the wrench head from the fastener and repositioning the wrench.