Doro (道路) is a word of Chinese origin. It usually means a relatively broad, paved road.
Michi (道 or 路) is a pure Japanese word and it has much broader meanings. It can mean a road, highway, street, avenue, path, passage, lane, alley, or a way of any width. Unlike doro, it can also figuratively mean a way, course, choice, means, duty, morality, teachings, justice or the like.
I will show you a few examples of its figurative uses:
仏の道 (hotoke no michi) = Buddha's teachings
人の道 (hito no michi) = moral principle
柔の道 (yawara no michi) = the art of judo