When there's devastation, there's terrible destruction. You can see the devastation from a violent hurricane and feel devastation over all the people that were injured.
When a natural disaster causes widespread death and destruction, that's devastation. This is a strong word that suggests serious damage has occurred, leaving almost nothing left. One knocked over car isn't devastation, but a whole town being wiped out is. People can also feel devastation — it's a kind of extreme sadness or state of feeling emotionally wrecked.