gadget vs gizmo

gadget and gizmo both are nouns.

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

As nouns, gadget and gizmo are synonyms defined as:

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

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

gadget (noun)	gizmo (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