mod con vs gismo

mod con and gismo both are nouns.

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

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

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

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

mod con (noun)	gismo (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