Executor is a simple interface in Java that defines a single method execute(Runnable command) for executing a task in a background thread. It is the simplest interface for asynchronous processing of tasks.
On the other hand, ExecutorService is a more powerful interface that extends Executor. It provides more advanced features like task scheduling, task cancellation, and returning the result of a task.
The ExecutorService interface defines a variety of methods for submitting tasks for execution, such as submit(), invokeAny(), and invokeAll(). It also provides methods for controlling the lifecycle of the executor, such as shutdown(), shutdownNow(), and isShutdown().
One important thing to note is that while Executor and ExecutorService are related, they are not interchangeable. Executor is a lower-level interface that is typically used by libraries or framework developers, while ExecutorService is a higher-level interface that is typically used by application developers.
In general, you should use ExecutorService when you need more advanced features like task scheduling or returning the result of a task, and use Executor when you only need to execute a task in the background without any additional features.
