using System;

​

public class Program

{

    public static void Main()

    {

        var dateTimeFormat = "yyy-MM-dd HH:mm";

        var dataUm = new DateTime(2019, 08, 01, 13, 48, 20, 999);

        var dataDois = new DateTime(2019, 08, 01, 13, 48, 20);

        Console.WriteLine(dataUm.ToString("yyyy-MM-dd HH:mm:ss.fff"));

        Console.WriteLine(dataDois.ToString("yyyy-MM-dd HH:mm:ss.fff"));

        Console.WriteLine(dataUm == dataDois);

    }

}