This is a generalized category, which includes all the sports played with the help of racquet. The basic difference between these categories is that all of them make use of racquets of different shape and size, also the ball used is of different shape and size.
Some of them are even played as indoor games. Here is a basic description of all such sports in short, also the pictures included with each category helps you in getting a better understanding of the sport.

Badminton	Squash
Table Tenis	Tennis

The most common and well known racket sports are tennis, badminton, table tennis and squash. Every category has its own specialty and requirements, also the equipments used are different. Like in the sport tennis the racket used have a greater surface area for hitting the ball, in badminton the racquet used is light in weight and the shuttlecock is also light in weight, the racquet used for table-tennis is small in size and rightly so as the table is also small. But the racquet used in squash is quiet similar to the racquet used in tennis, the main difference is in the area available for hitting the ball.