gizmo vs gadget

gizmo and gadget both are nouns.

Word	Noun	Adjective	Verb	Adverb
gizmo	Yes	No	No	No
gadget	Yes	No	No	No

As nouns, gizmo and gadget are synonyms defined as:

gizmo and gadget: a device or control that is very useful for a particular job

Other synonyms of gizmo include appliance, contraption, contrivance, convenience, gismo, widget.

gizmo (noun)	gadget (noun)
a device or control that is very useful for a particular job	a device or control that is very useful for a particular job
something unspecified whose name is either forgotten or not known