mod con vs gizmo

mod con and gizmo both are nouns.

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

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

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

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

mod con (noun)	gizmo (noun)
modern convenience; the appliances and conveniences characteristic of a modern house	a device or control that is very useful for a particular job
	something unspecified whose name is either forgotten or not known