Devices are the electronic products in which external power is required to make use of it.
Ex: Mobile phones,laptop,maximum of all electronic gadgets etc.,
Instruments are the tools in which external power is not required to make use of it. Instruments are the tools which are used to take measurements like measuring the length,profiles,curvatures,angles etc..,
Ex: Vernier calipers, Screw gauge. Sine bar, Bevel protractor etc..,