muling = the study of mules
twinking = winking and twitching at the same time
muling is movign items from 1 character to another or storing items of a charatcer youll never actualyl paly, but for safe keeping, most commonly with ATMA, twinking is the same kinda hting.
Muling is transfering items off your char to a stash or mule and twinking is taking those items that have been saved and using them on another char. This is usually done via ATMA, which you can find out more about in the sticky on the main page of the SPF.