Speedskates loosely defined have five wheels per skate, while rec skates have four wheels per skate. Actually, a more accurate measure would be the length of the frame to which the wheels are attached. A frame which has to accomodate five wheels is generally going to be longer than one designed for four wheels, although some "stretched" four-wheel frames also exist with larger spacing between the wheels. These could also be considered speedskating frames. The boots of speedskates are also generally lower cut than rec skates and are designed to hug the foot completely, often being made of high-tech materials like kevlar which can be "heat molded" so that they can be more precisely shaped to the individual foot. Rec skates in contrast tend to have some kind of rigid outer plastic shell or cuff which surrounds or supports an inner liner or softer shoe. Speedskates weigh considerably less than rec skates, and due to their more precise fit can be controlled with considerably more finesse than rec skates. Speedskates also tend to not have brakes. :)