Don't settle for success, strive for Significance
My colleague and I both have not read the book (nor heard the cassette). We were speculating what is meant by Significance that is beyond success.
Our guesses are:
Having not read the book, either, I would speculate that the difference is as follows. One can be successful at doing almost anything, but does that success have any significance, any value, any meaning? For example, one could be very successful at project management, but if the projects do not result in anything of true value, was the success significant?