What is the difference between creating a thread via ExecutorService and via new Thread?

The main difference between creating a thread via new Thread() and using ExecutorService lies in managing the lifecycle and scalability:

• new Thread() creates a new thread directly. It's simple but inefficient for a large number of tasks, as each thread consumes OS resources, and creating/deleting threads is costly.

• ExecutorService is a high-level API for managing a thread pool. It allows reusing threads, managing task queues, controlling the number of concurrently running threads, and shutting down properly.

Example of using ExecutorService:

ExecutorService executor = Executors.newFixedThreadPool(5);
executor.submit(() -> {
    // task
});
executor.shutdown();

Using ExecutorService is preferable in production code for efficient multithreading management, resource leak prevention, and performance enhancement.