The two are a similar instrument. It’s called Allen wrench as it is named after its creator – William G. Allen for his Allen Manufacturing Company in the mid-1900s. The organization centers around produce hexagonal screws and wrenches to attach those screws. The wrenches are then named after the proprietor, Allen wrench. From that point forward, different organizations began to fabricate a similar sort of wrenches, and that is the point at which the name “hex keys” exists.