Accountability vs Responsibility (the shortest version)
Accountability: Success or failure effect your account.
Responsibility: you have the ability to respond.
I’d say Accountability is a single-point blame mechanism, usually I hear it in a sentence like “who is accountable in case of a failure” (or: who do we fire), and it is given by a manager.
While Responsibility can be shared (in an agile team, everyone is responsible), mainly is forward-looking (since we can’t change the past), and often is taken by an individual.