The 'you are looking' version is a continuous tense form. It therefore has an implication of a longer time-frame. So, perhaps you would say 'you look' to someone who has just come back from a run, but 'you are looking' to someone who has been working hard at work for a few weeks. That's only an implication though. In many cases you can use either if you like.

creo que no hay ninguna diferencia, el sentido de la frase es la misma, solo usas alternativas para escribirla :)