To get a good finish with these 'vapor hone' machines there is still an abrasive blast cleaning step used to remove contaminates and produce a rough surface finish, then low pressure fresh glass beads compress the small peaks produced in a gentle way similar to ball burnishing to leave a smooth finish.
The water stream is more effective than using air at moving large amounts of media but the same results can be obtained in a conventional dry cabinet.
Put simply, the term vapor hone is just a marketing gimmick. We can all fabricate some grand words for a conventional blast cabinet as well, doesn't change the process though. It's all rather simple but takes a bit of experience and a good amount of time to get right.
I apologize for the poor quality of the first picture but it shows clearly the difference between a fine abrasive silicon carbide grit and the final low pressure glass bead blasting, all done in a dry cabinet. Glass beads were sprayed at 20-25psi and many cheap cabinets simply won't flow at that pressure.