I've not seen a response to your question about the difference
between rotary and vibratory tumblers.
The rotary tumbler is a round cylindar shaped barrel that is placed
on its side, resting on two rollers that rotate. The barrel rolls
around on those rollers.
The vibratory tumbler has some different shapes, but the most common
is that of a bowl atop a platform which vibrates. The bowl shakes,
as do the contents.
Both types allow the media to rub against the material to be buffed,
smoothed, or polished.
A jewelry tool catalog will have pictures and additional details
about the various media to be used.
Judy in Kansas