What's the difference between sails?

Wave - Speed - Freestyle ??

And plenty more!

Each sail type has it's own characteristics that suit what kind of fun you're looking to have:

 Speed

These sails are all about going quick in a straight line.   If you to travel at the speed of sound, then speed sails will help you get close.   They have are designed to present the most efficient shape possible to the wind, and part of this is achieved through "cambers".  These are inside the sail and clip onto the mast and lock in the shape to maximise the airflow over the sale.    Turning the sail at the end of a run takes a little extra effort as you need to flick the sail agressively to flick the cambers to the other side of the sail.  

Tuning a speed sail to extract maximum speed is great fun and can become a technical as you'd like.   Many of the pro's record measurements such as boom height, downhaul and outhaul after each session so they can accurately reproduce a sweet setting.   Most slalom/speed sails are from 6.0 to 10.0 metres.
 
 Freestyle

Freestyle is a totally separate discipline which requires power, strength, lightness and great handling all from the one sail.   It's a sail that is midway between the hardcore racing sail and the hardcore wave sail.   It may have moderate reinforcement because you may find yourself in the waves some days.   It's got a "cut" that means it will rig like it's got physical cams, which gears it towards a powerful shape, yet retains fast maneuverability for tricks and wave riding.   Some versions may even feature a cam or two.   Freestyle sails are generally around 5.5 to 7.5 metres in size.
 
 Wave

Wave sales are generally reinforced to be able to handle the beating they'll receive when you get it wrong.   Put a slalom sail in a breaking wave and it'll probably surface with a few panels missing and your day is done.  Wave sails are also made for rapid changes in direction, and ease of handling.   You won't find any cams which makes them easy to gybe.   The rear of the sale is also cut high to avoid getting it caught in the wave.  Sizes are generally 3.5 to 5.5 metres.  Wave sails are generally rigged on softer masts than speed sails.
 
Beyond these general overviews of the basic sail types, you'll find that different brands of sail focus on other areas you might like from a sail:

   * Powerful "bottom end" power to help you get on the plane
   * Easy to rig
   * Upwind performance
   * Construction - weight/strength