What's the difference between monitoring and observability?

Charity Majors has some (strong) opinions about the differences.  Fundamentally, monitoring is to keep track of known unknowns (1OI or first order of ignorance). Observability is to speed detection, diagnosis, and recovery from unknown unknowns (2OI or second order of ignorance).  She articulates in great detail what all she considers requisite for true observability and creates an awesome wishlist.  I stumbled upon her definition because I was reading Charity's recent article expressing her views on the evolution of the operations role in an organization.