Women's Saddles
Because women's hips are, on average, wider than men's, women's saddles are usually wider and also shorter. You can start with the women's version as you are learning which features best suit you, though you may find that you are comfortable on men's saddles.
Different Bikes, Different Saddles
Saddles are shaped to accommodate different seating for different kinds of bikes. Touring bikes, for example, require more upright seating than road bikes, which demand the rider to lean forward in a more aggressive, powerful stance. The cruising bike lends to a more cushioned, wider saddle.
Width
The width of the saddle is significant. When sitting, your bones should rest in the middle of each side of the saddle. If they rest too far apart, the saddle is too narrow and your sitting bones will hang over the edge, creating pressure. If they are too close together, the saddle is too wide, which can cause chafing.
Special Features
Some saddles have special features for added comfort. If you experience discomfort due to the seat's nose, consider "cutaway" seats, which have a channel running down the middle and/or holes near the end of the seat. This space relieves pressure between your sitting bones. If the seat is too stiff, consider a saddle made of foam. Saddles that are too soft, such as those made of gel, can increase pressure and chaffing.