Allen keys, also called hex keys, feature a hexagonal cross section, while Torx keys feature a star- or asterisk-shaped cross section. Torx is a registered trademark of CamCar, a division of Textron, while Allen keys were developed by the Allen Manufacturing Company of Hartford, Connecticut.
These two tools, along with conventional Phillips and flat-head screwdrivers, all perform the same basic function of fastening bolts and driving screws into materials for a tight fit. These tools cannot be used interchangeably and are often differentiated by shape and size for specific industries. One of the major benefits of Torx screws when compared with Phillips or hex screws is that they are less susceptible to cam-out, making it more difficult to accidentally damage the screw head by applying too much force.
Allen keys are commonly used for small industrial products and are often found on musical instruments such as electric guitars. Torx screws are frequently found inside automotive engines and consumer electronics devices such as laptop computers, with the most visible examples being internal hard drives and shell components for Apple MacBooks and MacBook Pros. The additional stability that Torx screws offer make them useful in any application where precision is preferable to overt force.