What's the difference between a lever (Medela Harmony) pump and a silicone (Haakaa) pump?

Lever pumps such as the Medela Harmony and Lansinoh use a hand-squeezed piston to actively express milk, so they can drain a breast. Silicone pumps like the Haakaa and Boon Trove use gentle passive suction and are best at catching let-down and leaks on the opposite breast. Community reviewers caution that silicone pumps draw mostly foremilk and won't fully empty a breast.