How does Julia handle concurrency vs parallelism?

Concurrency handles task interleaving, while parallelism executes tasks simultaneously using threads or processes.

Julia separates concurrency (task scheduling) from parallelism (simultaneous execution). Concurrency is handled via Tasks and async scheduling, while parallelism is achieved via threads (Threads.@threads) or distributed processes. Julia avoids a global interpreter lock, enabling true parallel execution on multi-core systems.