When I was working on making a fast draining mix the guy at the nursery told me to use pumice instead of perlite so I did. Was that a mistake or will they give the same results?

I would not say the correct wording is "a mistake". In the past I have used both perlilte and pumice. Looking back on the results, I much prefer perlite. However, one must be VERY CAREFUL concerning the type of perlite that is used. Generally, the grade offered by the industry is a small grind perlite, containing a lot of fines. This inferior perlite is trouble. The orchid industry puts out a 1/2 inch sized grade, that has a minimal fine content. I highly, highly, highly recommend it. - Millet