League of Legends has a relatively stable metagame. AD carry and a support go bottom, an AP carry goes mid, and a sustainer (tank) goes top, with the 5th man- an all but required jungler, left to his devices. These roles have not changed in at least a year of high level gameplay and across multiple tournaments
Dota 2 has an incredibly versatile metagame. The meta itself changes with every patch. Jungling heroes are not that common, there are two-lanes, tri-lanes where three allied heroes on the same team group remain in close proximity from the beginning of the game, as well as roamers, when one or more heroes are not on a lane, but are going around the map (roaming) assisting other teammates and trying to score an early kills. Lanes and roles are complex to the point where attempting to define many heroes, or even predicting how a single 5-hero composition will lane, becomes difficult.