In the episode Utopia, Captain Jack rides on the outside of the Tardis as it travels to the end of the universe. The end result is that he is dead by the time they reach Utopia. As common as that is for Jack, a death is a death.
Now, in the Time of the Doctor, Clara tries to get back into the Tardis after it tries to leave her on Earth. She has the key in the door and she rides on the outside of the Tardis as it makes its way back to Trenzalore through the time vortex.
So, why did Jack die, yet Clara didn't?