What's the difference between a canoe and a kayak? - Yahoo! UK & Ireland Answers
To sum it up,
"Kayak paddlers are using a double blade paddle, while canoes are paddled with a single blade paddle."
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The difference is how many blades does a paddle of the boat has.
If you see a single blade paddle, you can call it a canoe,
and if you see a double blade paddle, you can call it a kayak without hesitation.
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A riddle
Question;
If you see a hexaploid blade paddle, what do you call the boat?
Answer;
It's a motor boat. And the hexaploid blade paddle is called "a propeller".
