What is the deffierence betweent managed thread and unmanaged thread

public partial class Form1 : Form
{
    MOUSEHOOK mouseHook = new MOUSEHOOK();
    MOUSEHOOK.HookHandle hookhandle = null;
    MOUSEHOOK.MouseHookStruct mhs = new MOUSEHOOK.MouseHookStruct();

    public Form1()
    {
        InitializeComponent();
    }
    private void Form1_Load(object sender, EventArgs e)
    {
        hookhandle = new MOUSEHOOK.HookHandle(HookProc);
        if (true == mouseHook.InstallHook(hookhandle))
        {
            Console.WriteLine("successed");
        }
        Console.WriteLine(Thread.CurrentThread.ManagedThreadId.ToString());//10
        Console.WriteLine(AppDomain.GetCurrentThreadId().ToString());//2588
    }


    //hook procedure
    int HookProc(int nCode, int wParam, IntPtr lParam)
    {
      Marshal.PtrToStructure(lParam, mhs);
        switch (wParam)
        {
            case MOUSEHOOK.WM_LBUTTONUP:
                Console.WriteLine("how many times to enter？");//here print the sentence two times,
                break;
            default :
                break;
        }

        return MOUSEHOOK.CallNextHookEx(0, nCode, wParam, lParam);

    }



}
//hook class
public class MOUSEHOOK
{
    [DllImport("user32.dll")]
    private static extern int SetWindowsHookEx(int idHook, HookHandle HookProc, IntPtr hMod, int dwThreadId);
    //cancel
    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    private static extern bool UnhookWindowsHookEx(int idHook);
    //call next hook proc
    [DllImport("user32.dll")]
    public static extern int CallNextHookEx(int idHook, int nCode, int wParam, IntPtr lParam);
    [DllImport("kernel32.dll")]
    public static extern int GetCurrentThreadId();

    [StructLayout(LayoutKind.Sequential)]
    public class POINT
    {
        public int x;
        public int y;
    }
    [StructLayout(LayoutKind.Sequential)]
    public class MouseHookStruct
    {
        public POINT pt;
        public int hwnd;
        public int wHitTestCode;
        public int dwExtraInfo;
    }

    public const int WH_MOUSE = 7;
    public const int WM_MOUSEMOVE = 0x200;
    public const int WM_LBUTTONDOWN = 0x201;
    public const int WM_LBUTTONUP = 0x202;
    public const int WM_NCLBUTTONDOWN = 0xA1;
    public const int WM_NCLBUTTONUP = 0xA2;
    public const int WM_NCMOUSEMOVE = 0xA0;
    public MouseHookStruct mhs = new MouseHookStruct();
    public int hhook;
    public delegate int HookHandle(int nCode, int wParam, IntPtr lParam);

    public bool InstallHook(HookHandle MouseProc)
    {
        hhook = SetWindowsHookEx(WH_MOUSE, MouseProc, IntPtr.Zero, GetCurrentThreadId());//AppDomain.GetCurrentThreadId()
        if (hhook != 0)
            return true;
        return false;
    }
    public void UnInstallHook()
    {
        bool ret = false;
        if (hhook != 0)
            ret = UnhookWindowsHookEx(hhook);
        if (ret)
            hhook = 0;
    }
}