De quanto tempo passei com threads em Java, encontrei essas duas maneiras de escrever threads:

Withimplements Runnable:

public class MyRunnable implements Runnable {
    public void run() {
        //Code
    }
}
//Started with a "new Thread(new MyRunnable()).start()" call

Ou comextends Thread:

public class MyThread extends Thread {
    public MyThread() {
        super("MyThread");
    }
    public void run() {
        //Code
    }
}
//Started with a "new MyThread().start()" call

Existe alguma diferença significativa nesses dois blocos de códig