No idea of what you are trying to do. Nothing really makes sense. However, here is how you can compare:
class Program
{
enum Grade { Low = 1, Medium = 2, High = 3, Maximum = 4 }
[Flags]
enum GradeFlags { Low = 1, Medium = 2, High = 4, Maximum = 8 }
static void Main(string[] args)
{
foreach (var enumValue in Enum.GetValues(typeof(Grade)))
{
Console.WriteLine("{0} - with flag: {1}", (int)Enum.Parse(typeof(Grade), enumValue.ToString()), (int)Enum.Parse(typeof(GradeFlags), enumValue.ToString()));
}
Console.ReadLine();
}
}