Ncassidine, what are you saying is the difference between illusionist and magician? I think of the two terms as interchangeable.
I saw Secret at the Atlantic and enjoyed it. I was actually one of the audience participants. I used to be a mild magic buff, so I know how a lot of tricks are done (including the one I was involved in). With both his show and Penn and Teller's show at the Marquis, I know how almost all the tricks were done, but they know how to entertain.
I saw In and Of Itself with Derek DelGaudio, and I have no idea how many of the tricks were done. I was completely baffled by a lot of it (although I think I know how he did the big trick at the end). But he is not really a showman, so the experience is different than at a show like Penn and Teller.