What is three things that bat wings have that bird wing dont have?

Bat wings have a flexible membrane made of skin called the patagium, which extends between elongated finger bones, allowing for greater maneuverability in flight. Additionally, bats possess a unique bone structure with elongated phalanges that support the wing, unlike the rigid structure of bird wings. Lastly, bats have a highly developed echolocation system that aids in navigation and hunting, a feature not present in birds.