oar v. paddle

• An oar is held in an oarlock, which acts as a fulcrum. A paddle is not captive, and can be moved freely.
• One rows with an oar, and paddles with a paddle.
• One faces backward to row, and forward to paddle.
• Oars are longer than paddles.
• Oars can be held with one or two hands. Paddles are held with two hands.
• Oars are used in pairs, and only have a blade at one end. Small craft can be propelled by a single paddle, and paddles may have blades at both ends.

Wikipedia on watercraft paddling