An enduro normally still has the original large diameter off-road style wheels, e.g., 21 inch front, 18/19 inch rear with (road legal) knobblies or road biased tires. A supermoto is basically an enduro with sportbike tires and rims, more powerful brakes, and, I think, sometimes a different suspension tune. Some people also call any small off-road bike "a supermoto", but that's not really correct either. The term "supermoto" was first used by Suzuki to describe its new smaller capacity version of the Enduro range that came out in 2003. The original definition was that it was all about function over fashion, with small wheels, a svelte frame, and an engine suitable for the job. Since then other manufacturers have jumped on the supermoto bandwagon, some making bikes that are almost entirely functional trials machines, while others take a more traditional off-road approach. In fact there are many different types of supermotors depending on who you talk to so here we'll just go with what everyone else calls them: trials bikes, adventure bikes, dual purpose bikes, etc. Trials bikes are made for going fast, generally on dirt, sand, or grass. They usually come with flat bars, wide handlebars, and long legs which helps keep the center of gravity low for better traction. The engines are typically mid-range ones, around 100cc-125cc, because they need to be able to get up and down hills without breaking down.