A wood is an area covered in trees, larger than a grove or a copse. A forest is also an area covered in trees, but it is larger than a wood. The trees in woods and forests grow thickly, and the space between them is overgrown with grasses, shrubs and underbrush. The U.S. National Vegetation Classification system differentiates them according to their densities: 25 to 60 percent of a a wood is covered by tree canopies, while 60 to 100 percent of a forest is canopied.
While the dictionary does not give further distinguishing information, historically woods and forests were not the same thing. In English history, woods were simply areas covered in trees. Forests, however, were similar to modern wildlife preserves. They were places where deer and other wild creatures could live and wander freely, protected by the king's laws. Forests were not necessarily woodland at the time; heaths and pastures could also be forests, if they were designated areas where wild animals were under the king's legal protection.
Jungles are like woods and forests in that they are covered in trees, but they are also full of vines, flowers, bogs, fungi and a vast array of animal and insect life. Jungles grow in tropical regions like Africa, South America, New Guinea and parts of Australia. They are damp, dense, thickly canopied forests with different kinds of plantlife than those found in the woods in temperate regions like England and the American Northwest.
Woods, forests and jungles are all full of life, but woods and forests are home to a different set of animals than jungles are. Woods and forests are populated by animals such as deer, bears, mice, chipmunks, squirrels, owls and weasels. Jungles are inhabited by snakes, monkeys, macaws and crocodiles and a multitude of other creatures. Jungles and rain forests support more species of animals, plants and insects per acre than any other places on Earth.