When I think of pot-shotters, three guys that come to mind are Floyd when he went up in weight, Roy Jones Jr., and an old Hopkins. I think of pot-shotters as fighters who like to mitigate danger and exploit an opponent's over-eagerness with well-placed single shots. All three men could fight in a variety of different ways (Floyd could fight extremely well behind an active jab and could throw great combinations when he wanted to; Roy could do pretty much whatever he wanted to in his prime, but tended to fall back on using his athleticism and staying on the outside while pot-shotting against his most dangerous opponents; towards the very end of his MW reign and throughout his LHW run, Hopkins' style became very defensive and goading his opponents into over-commiting, landing a well-timed right hand, and then smothering any work coming back), but when they wanted to fight safe, pot-shotting from the outside while taking minimal risk tended to be what they'd fall back on. I'd say that someone like Adonis Stevenson could probably be classed a pot-shotter, as well.
When I think volume puncher, guys like Paul Williams, Antonio Margarito, Joe Calzaghe, and, to name a current fighter, Jarret Hurd, come to mind (Calzaghe was more skilled than the rest, but he was still very much reliant on volume). Volume puncher is a pretty broad category which can encapsulate several different kinds of styles. Some guys are high-volume from the outside (guys like Khan, Usyk, or Santa Cruz would be good examples even though all three have distinct styles), whereas some guys are volume punchers who like to get inside (think guys like Armstrong, Qawi, Duran, or Frazier).