Explain the difference between abstraction and encapsulation, since interviewers often conflate them.

Abstraction is about the design view — exposing a simple, intention-revealing interface and hiding the complexity of how a job is done (e.g., a Repository interface hiding SQL).

Encapsulation is the implementation mechanism — bundling state with the methods that operate on it and restricting direct access to that state. Abstraction is 'what to expose'; encapsulation is 'how to protect what you hid'. You use encapsulation (access modifiers) to enforce the boundaries that abstraction defines.