Corded clippers are plugged into an outlet and will have a constant power source. Cordless clippers run on batteries and must be recharged after a specific time. Both have pros and cons, so it depends on your preference. Cordless clippers are more expensive, but you have the freedom to move around without being tethered to an outlet. Corded clippers are cheaper, and you don't have to worry about batteries dying in the middle of a grooming session.