Compare two objects for properties with different values

I improved a little on Krishnas answer:

public List<string> GetChangedProperties<T>(object A, object B)
{
    if (A != null && B != null)
    {
        var type = typeof(T);
        var allProperties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
        var allSimpleProperties = allProperties.Where(pi => pi.PropertyType.IsSimpleType());
        var unequalProperties =
               from pi in allSimpleProperties
               let AValue = type.GetProperty(pi.Name).GetValue(A, null)
               let BValue = type.GetProperty(pi.Name).GetValue(B, null)
               where AValue != BValue && (AValue == null || !AValue.Equals(BValue))
               select pi.Name;
        return unequalProperties.ToList();
    }
    else
    {
        throw new ArgumentNullException("You need to provide 2 non-null objects");
    }
}

because it wasn't working for me. This one does and the only other thing you need to make it work is the IsSimpleType()-Extension Method that I adapted from this answer here (I only converted it into an extension method).

public static bool IsSimpleType(this Type type)
{
    if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
    {
        // nullable type, check if the nested type is simple.
        return type.GetGenericArguments()[0].IsSimpleType();
    }
    return type.IsPrimitive
      || type.IsEnum
      || type.Equals(typeof(string))
      || type.Equals(typeof(decimal));
}

Try this. should be generic for any class.

 public List<string> GetChangedProperties(object A, object B)
    {
       if (A!= null && B != null)
        {
            var type = typeof(T);
         var unequalProperties =
                from pi in type.GetProperties(BindingFlags.Public | BindingFlags.Instance)
                where pi.GetUnderlyingType().IsSimpleType() && pi.GetIndexParameters().Length == 0
                let AValue = type.GetProperty(pi.Name).GetValue(A, null)
                let BValue = type.GetProperty(pi.Name).GetValue(B, null)
                where AValue != BValue && (AValue == null || !AValue.Equals(BValue))
                select pi.Name;
     return unequalProperties.ToList();
         }
    }