[Cory]

As refered to on CD--

Crab- having all wheels rotate together (ie: locked to the same angle). Derived from the ability of a crab to scuttle in any direction.

Swerve- Either all wheels can independently rotate, or they rotate in sets of two. Allows you to both translate and rotate, as well as drive the robot using ackerman steering, or monster truck steering where the front wheels turn one direction, and the rear in the opposite direction.