Foresters are the scientists who manage forests to keep them healthy and help people understand and use the forest wisely. The main job of foresters is to manage the forest and help trees grow. They measure trees. They fight forest fires and plan how to prevent fires. They decide when it is time to harvest, or cut down, trees.
Forest rangers are the forests' friends too.
Their job is to help people understand and enjoy the forest. They teach people how to enjoy the forest without hurting it by causing fires, throwing away litter, or destroying plants. Not all scientists wear white coats and work with test tubes in laboratories. Many kinds of scientists work in the forest. For them the forest is like a big laboratory.