Trees and shrubs are self-supporting.
Vines climb on other plants or on inanimate structures like a fence or a wall.
This strategy allows them to get closer to the sun. All plants are in competition with each other for sunlight, which is the energy source that they capture to power photosynthesis within their cells. Any plant that can grow taller than its neighbors will be more successful in this competition. A woody stem allows this. In order to move water and nutrients efficiently within themselves, woody plants had to develop a plumbing system.