Hummingbird feeders hold liquid and have very narrow openings. Platform feeders are simply flat tables raised off the ground. Cardinals like these. Doves will eat from them too if they are not very far off the ground. Shorten the perches to keep larger birds away.
Hopper feeders are bins that hold seeds that spill out of the bottom as the birds eat.
Suet feeders are wire or mesh baskets that hold suet or pre-packaged suet cakes. Bowl feeders are hanging bowls that typically are covered by a large plastic dome to keep out the rain and snow. It is extremely important that you clean your feeders at least once every two weeks. Let the feeders air-dry before rehanging them. When you refill feeders, shake out damp seeds that may become moldy.