There are different types of pruners and loppers: the bypass syles gives a cleaner cut; the anvil style are great for thinning shrubs.

Anvil pruners and loppers have a blade that closes against a piece of softer metal called the anvil. They can crush or shred what's being cut and are primarily used for thinning out plants -- such as cutting dead material or for thinning brush.

Bypass pruners and loppers have a blade that sweeps past the lower jaw like a giant scissors. They are used for razor-clean cuts that can affect the health of the plant if not done precisely. Blades should be kept razor sharp.