Show shovels typically have wooden or metal handles, but can have blades made of either plastic or metal. They're one of the few kinds of shovel that is made from either material. A plastic snow shovel may be preferable because it's slightly lighter than a metal one. Additionally, a plastic shovel is better to use if you're shoveling a wooden deck, as it's less likely to damage the wood.
Garden shovels such as spades are typically made of metal, which is necessary to help you dig through earth and rocks. A plastic shovel wouldn't stand up to this type of digging, nor would it allow you to stand on it to push it down into the earth. The only garden shovel made of plastic that you mind find in a store is a small hand trowel, which you use for moving dirt in small planting holes in loose garden beds, rather than digging large holes in solid dirt.
Oftentimes, shovels built for childrens are made of plastic to make them lighter and safer. These shovels make take the shape of a garden shovel or snow shovel, and are as much a toy for the child as an actual tool. Kids also use plastic shovels or trowels at the beach to make sandcastles.
Though a metal shovel is designed for heavy-duty digging, a plastic shovel may be suitable for less-arduous outdoor tasks, such as digging dirt or sand out of a pile and into a wheelbarrow to relocate it. You may choose to use a plastic shovel if you find the metal one too heavy, especially during periods of prolonged use. Remember that plastic shovel blades will wear down when ground against hard objects, such as gravel.