What is the difference between runnable and callable in Java?

// importing build-in classes
import java.util.concurrent.*;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

// class impelementing callable interface
public class EdPresso implements Callable<String> {
 
    @Override // overriding method 
    public String call() throws Exception {
        Thread.sleep(500);
        //return the thread name executing this callable task
        return Thread.currentThread().getName();
    }
     // main method starting here
    public static void main(String args[]){
        // Thread pool size is 5
        ExecutorService exe = Executors.newFixedThreadPool(5);
        //Create EdPresso instance
        Callable<String> callable = new EdPresso();
        //create a list to hold the Future object associated with Callable
        List<Future<String>> mylist = new ArrayList<Future<String>>();
        for(int i=0; i< 50; i++){
            //submit Callable tasks to be executed by thread pool
            Future<String> store = exe.submit(callable);
            //add Future to the list, we can get return value using Future
            mylist.add(store);
        }
        for(Future<String> i: mylist){
            try {
                // because Future.get() waits for task to get completed
                System.out.println(new Date()+ "::"+i.get());
            } catch (InterruptedException | ExecutionException e) {
                e.printStackTrace();
            }
        }
        //shut down the service now
        exe.shutdown();
    }
}

// EdPresso class implementing
// Runnable interface
public class EdPresso implements Runnable {
    public static void main(String[] args) {
        EdPresso ob1 = new EdPresso();
        Thread thread = new Thread(ob1);
        thread.start();
        System.out.println("Output for code outside the thread");
    }
    public void run() {
        System.out.println("Output for the part running inside the thread ");
    }
}