mod con vs gadget

mod con and gadget both are nouns.

Word	Noun	Adjective	Verb	Adverb
mod con	Yes	No	No	No
gadget	Yes	No	No	No

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

mod con: modern convenience; the appliances and conveniences characteristic of a modern house
gadget: a device or control that is very useful for a particular job

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

mod con (noun)	gadget (noun)
modern convenience; the appliances and conveniences characteristic of a modern house	a device or control that is very useful for a particular job