How to compare nullable types?

C# supports "lifted" operators, so if the type (bool? in this case) is known at compile you should just be able to use:

return x != y;

If you need generics, then EqualityComparer<T>.Default is your friend:

return !EqualityComparer<T>.Default.Equals(x,y);

Note, however, that both of these approaches use the "null == null" approach (contrast to ANSI SQL). If you need "null != null" then you'll have to test that separately:

return x == null || x != y;

Nullable.Equals<T>?

if (x.Equals(y)) 

You can use the static Equals method on System.Object:

var equal = object.Equals(objA, objB);