Walking is better than running in terms of benefit vs risk. Walking offers the same benefits as running without injury risks. Walking is still a cardiovascular exercise, however, it is not high impact like running is.
When comparing walking and running in terms of calories burned for the time allotted, you will definitely burn more calories running.
We see this being the opposite case when comparing the two in terms of distance traveled.
In comparison, walking a mile a lot of times will burn more calories than running a mile. There are of course some instances where this is not the case but predominately it is.