As bears evolved into omnivores, which means they began to include plant material in their diet, their gut became longer. Since plants take longer to digest than meat, plant eating animals need longer guts than carnivores. The bears teeth also changed over time. Canids tear their food when they eat, and have typical carnivorous teeth - small pointed front teeth and pointed molars. But bears crush and grind their food and therefore have short front teeth and rounded molars.
Bears differ from the canids in other ways too.
We have all grown up with the story of how when fall comes, the temperatures begin to drop and bears go into hibernation for the winter. Hibernation is a way for animals to avoid many of the stresses of winter. But bears are not true hibernators. It is during January and February of this winter dormancy period that the young baby bears arrive. Born naked and blind, newborn cubs weight as little as a half a pound.