Rubicon vs demarcation

Rubicon and demarcation both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rubicon	Yes	No	No	No
demarcation	Yes	No	No	No

As nouns, demarcation is a hypernym of Rubicon; that is, demarcation is a word with a broader meaning than Rubicon:

Rubicon: a line that when crossed permits of no return and typically results in irrevocable commitment
demarcation: a conceptual separation or distinction

Other hypernyms of Rubicon include contrast, dividing line, line.

Rubicon (noun)	demarcation (noun)
a line that when crossed permits of no return and typically results in irrevocable commitment	a conceptual separation or distinction
the boundary in ancient times between Italy and Gaul; Caesar's crossing it with his army in 49 BC was an act of war	the boundary of a specific area