What is the difference between practice and tournament tennis balls?

Practice (pressureless) balls are put into a can which is not vacuum sealed. This keeps them more consistent with a lower bounce, but a longer "life span." They are also quite a bit lighter than tournament balls, and are good for rehabilitaion from injuries, especially arm injuries. Tournament (pressured) balls are put into vacuum sealed cans. They are less consistent, with a higher bounce, but are only good for a certain amount of time, depending on the caliber of player. They are heavier, giving them more momentum. Hope this helped.

Practice balls are the same as regular balls as far as how they play. A slight flaw in the factory on a batch of balls deems them unable to be sold as regular can. An example would be if the yellow dye came out a very slight shade darker than it should be, they may make 20 thousand balls that have that color practice balls. Another reason may be if there is too much white rubber, or it is too thick. If you order personalized balls for an event, or a club etc. they may sell you 50 cases, but they may make 100. Sometimes practice balls come with a logo. The only drawback would be that you dont get a # on the balls to seperate from other balls. I use them all the time..

Practice Tennis Ball : Poor in quality,

Tournament Tennis Ball : Very Excellent in quality

the non pressured practice balls wear out faster, pressurized practice balls are like regular ones but has"cosmetic defects" what ever that means