std::static_pointer_cast vs static_cast

I have a class hierarchy and in it B is derived from A like this:

class A : public std::enable_shared_from_this<A>
{

};

class B : public A
{
   void f()
   {
        // the code below compiles
        std::shared_ptr<B> copyOfThis = std::static_pointer_cast<B>(shared_from_this()); 
        // the code below does not
        std::shared_ptr<B> copyOfThis = static_cast<std::shared_ptr<B>>(std::make_shared<A>(shared_from_this()));
}
};