What is the difference between an external spline and torx?

An external spline is a series of ridges or grooves on the outside of a shaft or fitting that allows for torque transfer between connected components, typically used in mechanical applications like gears or couplings. In contrast, a Torx is a type of fastener characterized by a six-point star-shaped pattern designed to provide better grip and reduce cam-out compared to traditional screw heads. While both are used to transmit torque, external splines are primarily for coupling parts, whereas Torx is used for fastening.