Device comes from Latin dividere, meaning "something which is divided". Later with old French devis (disposition, desire, purpose, or decorative emblem) and deviser (arrange, plan). A device is something planned, designed, potentially intricate. A device doesn't always need to be mechanical/physical as there are "literal devices" and one can be "left to their devices". I'd say "device" is more like "a planned thing" if giving a basic definition.

A machine is almost always a device, but a device isn't always a machine. A fancy earring can be a device, but it is clearly not a machine.