That act of glass bedding the action and free floating the barrel are usually one process.
Free floating, is making sure that no part of the barrel touches the stock forward of the chamber.
Glass bedding is creating a custom tight fit of the action in the stock. (not the same as gluing it in the stock)
Pillar beading is the act of glass bedding and creating sleaves for the action screws to tighten 'onto' as they are screwed into the action. The benefit of this is that you can torque the screws evenly without wood or composite stock flex.
http://www.stockysstocks.com/pdf/pillarbedding.pdfhttp://www.scorehighgunsmithing.com/Does this always lead to more accuracy? Quite often it does. But a bad barrel will not be more accurate from just bedding the action. An action that is 'easily' removed from the stock will usually benefit from a bedding and freefloating job.
-Steve