The bad news is you probably can't tell them apart– there's technically ways to discern the two but you need a microscope or infrared visualization or the like. And most of us don't have night-vision goggles that will survive hauling around the swamp.
The good news is you don't need to tell them apart! Adulation, exclamation and reverence are equally appropriate reactions to both great and greater serpents of ronka, so you can just roll however you were gonna and it'll be fine. C:
