Each of these creatures has a trait that can be added or removed to your creature adoption.
Flutterns can have bat or bird wings. Rarely they'll have Flying-squirrel type wings, or Wyvern arm wings.
Here are the traits that both creatures can have:
Hind feet, no forelegs.
Big or little nose.
Big or little ears.
Up ears or lop.
Bunny nose or bat variety nose.
One to three eyes.
Open or closed ears.
Bunny, bat, or long and fluffy tail.
You can either make your own, or submit colors and traits, so that I can make one for you.