The renaissance artists differ from medieval artists in their treatment of religious themes by having very different views of the world through their artistic forms. The renaissance artists focused on humanity and less of what the churches wanted them to picture, which lead them to make realistic art. On the other hand the medieval artists had focused on the churches and their lord, than to focus on time for the arts. In the middle age they had to suffer from the plague, while the plague wiped out more than half of the population they had way more things to worry about than art.
I hoped that helped, Have a nice day.