Getting different output of the same program when written in C# and Java in multithreaded environment

I have a shared boolean static variable uninitialized and created two threads, started one thread, then sleep of two seconds and then started second thread.

I have print statements basically in both the threads based on the shared variable condition but I am getting different output when ran in c# and java

C# code:

class ThreadCache
    {
        public static bool shared;
        public static void Main()
        {
            new Thread(Meth1).Start();
            Thread.Sleep(2000);
            new Thread(Meth2).Start();
        }
        public static void Meth1()
        {
            while (!shared) { }
            Console.WriteLine("Hello");
        }
        public static void Meth2()
        {
            shared = true;
            Console.WriteLine("Hi");
        }
    }

Java Code:

public class HiHello
{
    static boolean S1 = false;

    public static void main(String[] args) throws InterruptedException {
        new Thread(new Thread1(), "Thread 1").start();
        Thread.sleep(2000);
        new Thread(new Thread2(), "Thread 2").start();
    }

    private static class Thread1 implements Runnable
    {
        public void run()
        {
            while (!HiHello.S1) {}
            System.out.println("HELLO!");
        }
    }

    private static class Thread2 implements Runnable
    {
        public void run()
        {
            HiHello.S1 = true;
            System.out.println("HI!");
        }
    }
}

In C# whatever number of times I run the code I get both outputs "Hi" and "Hello" but when I run in java only "Hi" gets printed and the programs never terminates(exits). Please explain me the reason of getting different outputs