What is the difference between a duck?

I'm going off to Florida tomorrow to chill with Seth and his grandparents. Good times and good weather ahead! Look out for ducks flying north, pilot! Hopefully catch a Sox game or two at Fort Myers. By the way, the answer to the title riddle is: One leg is the same.

(c.f.: Duck-bar jokes; Frank Answers)
(Further note: "Protolanphism" does not exist)