What is the difference between racquetball and tennis?
While racquetball and tennis are similar in that they both involve using a racquet to hit a ball back and forth, there are many differences between racquetball and tennis.

Racquetball is played in an enclosed room where players hit the ball back and forth against the same wall. In tennis, players also hit the ball back and forth but they hit it to each other over a net. In tennis, the ball has a fuzzy outer layer which causes the ball's trajectory to be more influenced by the spin on the ball. The rackets in tennis are larger and have higher tension.

A tennis court is much larger than a racquetball court measuring 78 ft long and 36 ft wide. This width is reduced in tennis to 27 ft for a singles match.

These are just a few of the differences but there are many more: scoring, attire, court markings, etc.