There are three main categories of differences between kayak paddles: composition, twist/feather, and shaft shape/length.
Earlier paddles were often made of wood and then later with a heavy metal shaft and poly-synthetic blades. Advances in technology today include carbon fiber shafts with foam and carbon fiber blades on the high end, and low flex but light plastic on the low end, sometimes with rubber grips.
Twist, or feather, indicates the degree to which one blade is offset in angle from another. A paddle with zero degrees of offset has two blades which are in line with each other. Historically, paddles had a 90 degree twist so that when one blade was in the water the other blade did not catch any air, and the upper wrist was well oriented to push the stroke through. Slalom kayakers continue to use a 90 degree twist but the rest of the whitewater community have moved to a range of no twist to 45 degree twist. One major reason for this is no twist blades are ideal for playboating due to a playboater’s need to engage both blades at once in certain moves, and move from one active blade to the other in a very short time period, not having time to twist. In addition, whitewater kayaking does not require paddling long distances on flat water where wind resistance of the upper blade is a factor.
Paddles with blades included historically measured over 200 cm, but now usually measure between 185 and 205 cm. Also the industry has begun to offer bent shafts that are ergonomically shaped to relieve stress off of the paddlers wrists. Many companies also offer specialized rubber grips to ease the paddlers grip and provide a place to feel where hands should hold the shaft. Small and regular shaft thicknesses may be available as well to offer smaller paddlers more comfort while gripping the paddle.
In addition to the boat and paddle there are several other pieces of gear that are necessary for whitewater paddling. A buoyancy aid (BA) or personal flotation device (PFD), helmet, and spraydeck (sometimes known as a sprayskirt) are considered essential while a rope throwbag, knife, and safety whistle are recommended as standard pieces of safety gear. Many people also wear nose clips since flipping the boat is a normal part of the whitewater experience. In addition the boater must be dressed appropriately for the water temperature, which might imply a wetsuit or drysuit. The boat itself should be equipped with enough flotation to make pinning less likely and help enable its recovery.