injector vs gadget

injector and gadget both are nouns.

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

As nouns, gadget is a hypernym of injector; that is, gadget is a word with a broader meaning than injector:

injector: a contrivance for injecting (e.g., water into the boiler of a steam engine or particles into an accelerator etc.)
gadget: a device or control that is very useful for a particular job

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

injector (noun)	gadget (noun)
a contrivance for injecting (e.g., water into the boiler of a steam engine or particles into an accelerator etc.)	a device or control that is very useful for a particular job
An injector, ejector, steam ejector, steam injector, eductor-jet pump or thermocompressor is a type of pump.