Glenn,
You are right, they do have slightly different shapes but the commonality is a longer and narrower blade than most. YC is correct, Badger does not label their paddles with traditional names but does refer to ottertail, beavertail and voyageur as the inspiration behind their shapes. 12 years ago I switched to a Greenland paddle for kayaking. These traditional Inuit paddles have long blades that are skinny. I prefer a 3 1/8" width that tapers down to 1 1/2" at the loom and each blade is 33" to 35" long. I find the paddles less stressful on the joints and more versatile than a short fat blade. I haven't used the ottertail canoe paddles that I have enough to corroborate an similar effect for me.
Dave