There's a huge difference between the two. Alan keyes appealed strictly to conservatives, that was the base and thats who he went for.
Dean mocks the people in the center, and tosses them into the radical right category.
Its one thing to appeal to your base, and use issues they want to hear to get there votes, its quite another to attack everyone else who is not in your base. Keyes never acted like those in the middle were liberals, he believed he could appeal to the base and that moderates would be drawn also by the same issues, but he didn't attack them, he attacked liberals. Dean attacks conservatives, and moderates since it appears he can't tell the two apart.