TimeSpan

using System;
using System.Timers;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            var time1 = "2010-5-26 8:10:00";
            var time2 = "2013-4-11 15:49:00";
            var t1 = Convert.ToDateTime(time1);
            var t2 = Convert.ToDateTime(time2);
            
            var timeSpan = t1 - t2;

            Console.WriteLine(timeSpan.Hours);
            Console.WriteLine(timeSpan.TotalHours);

            Console.WriteLine(timeSpan.Minutes);
            Console.WriteLine(timeSpan.TotalMinutes);

            Console.WriteLine(t1 - t2);

            var timeSpan1 = t2 - DateTime.Now;
            var timer = new Timer(1000);
            timer.Elapsed += (obj, ergs) =>
            {
                Console.WriteLine(timeSpan1.TotalSeconds);
                timeSpan1 = t2.Subtract(DateTime.Now);
            };

            timer.Start();

            Console.WriteLine("time out.");

            Console.Read();
        }
    }
}