this is from brian gordon in an article on the biomechanics of the serve
found at www.tennisplayer.net
The "foot up" and "foot back" terminology corresponds roughly to the common coaching terminology of "pinpoint" and "platform" stances, and this is the terminology I'll use. To be clear I'll refer to any serve where back foot movement occurs as "pinpoint" and any serve where no back foot movement occurs as "platform". This distinction between pinpoint and platform holds regardless of the relative distance between the feet.
But the platform stance has to be subdivided into narrow and wide designations, depending on the distance between the feet. By this designation, both Roger Federer (wide) and Andy Roddick (narrow) are platform servers
he goes on to say pinpoint can have 2 forms also where the back foot slides up but stays behind the front foot
and another version where the back foot slides up alongside or slightly in front of the front foot.
lastly he mentions the platform stance may preferentially give more horizontal drive to the leg push
whereas the pinpoint gives more vertical drive.
ill search to see if there is mention of control or power differences but i havent seen them yet