What is the difference between a widget and a gadget?

From the Cambridge dictionary (brief and precise):

Widget : any small device whose name you have forgotten or do not know, or an imagined small product made by a company

Gadget : a small device or machine with a particular purpose

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Widget according to the free dictionary online: on line is (Engineering / Tools) Informal any small mechanism or device, the name of which is unknown or temporarily forgotten.

Gadget according to the free dictionary online: May come from French gachette, which is or has been applied to various pieces of mechanism, or from Gaget, the person who created the first so-called gadgets---miniature Statues of Liberty sold in Paris---or from a Navy term for a tool or mechanical device for which one could not recall the name.