Difference between generic argument constrained to an interface and just using the interface

Question

What is the difference between this:

void MyMethod(IMyInterface value)
{
    //...
}

and this:

void MyMethod<T>(T value) where T : IMyInterface
{
    //...
}

Answer 1

The main functional difference is that you can know the actual type of the object inside of the generic method. The T parameter will contain the actual type which can advantageous in certain scenarios.

In the non-generic case you cannot guarantee access to the underlying type of the object. Most of the type you could grab value.GetType() but the user could pass Null and thwart you.