The hopper protects seed against the elements. Hopper feeders can be used to attract both small birds such as finches or large birds such as jays. With hopper feeders, be especially careful about regularly cleaning your feeder. Few hopper feeders do a good job of protecting seed from rain, and the seed can become moldy.
Most hopper feeders hold a good amount of seed.
Tube feeders generally keep the seed fairly dry. Tube feeders with short perches can be selective to smaller birds. For example, a tube feeder with small perches can accomodate chickadees, but exclude large birds such as jays. These feeders offer little protection against squirrels or the weather. Some tube feeders are equipped to attach a tray feeder to them.