Regular milk and evaporated milk is basically the same thing as in they're both the same milk that comes from the same cows.
But evaporated milk is different in that the evaporated milk is regular milk that goes through a cooking process to evaporate the water content in it so that it's more creamier than regular milk.
It makes it so that the milk is condensed down and great for cooking and even for using as coffee creamer.
When the milk is evaporated it becomes heavier and caramelized too.