I don't think that there was a version of CFMX For J2EE available before now that would have installed on Tomcat on the Mac. Prior installers would abort if not being installed on the Target platform.
During the latest Beta of the CFMX for J2EE, there was a separate version that was used for the Mac.
In any case, before now, there was no supported developer porduct for the Mac.
According to Macromedia, the performance difference is most significant on larger installations with multiple CPUs.
Based on my experience with the CFMX Standalone server used in the port, and the CFMX for J2EE in the beta -- they, indead are separate products. There are differences in the way the are deployed (directory tree), and there are different options for clustering, and other advanced options. For example, with CFMX for J2EE under JRun it is trivial to setup duplicate CFMX servers and cluster them and attain automatic load-balancing.
The CFMX for J2EE contains all the bits necessary to run Web Services.
Finally, if I belived that a company was trying to scam its customers, I would not use or recommend their products as a basis for building a web site.