Rubber is a natural polymer which possess elastic properties. It is a linear polymer of isoprene (2-methyl-l,3-butadiene).
In natural rubber, m-polyisoprene molecules consists of various chains held together by weak van der Waals’ interaction and has coiling structure. So, it can be stretched like a spring and it regain its original shape after force is released.
Plastics are synthetic or semi-synthetic polymers of organic compounds which possess intermediate intermolecular forces of attraction. It has linear, structure that can be moulded but cannot regain its original shape after stretching is over.