unstable vs precarious

unstable and precarious both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unstable	No	Yes	No	No
precarious	No	Yes	No	No

As adjectives, unstable and precarious are synonyms defined as:

unstable (adjective)	precarious (adjective)
lacking stability or fixity or firmness	fraught with danger
subject to change; variable	not secure; beset with difficulties
suffering from severe mental illness	affording no ease or reassurance
disposed to psychological variability
highly or violently reactive
affording no ease or reassurance