Although many types of tennis balls exist, perhaps the most marked distinction is between pressurized and pressureless balls. If you look at the anatomy of a tennis ball it is a rubber ball wrapped in a fuzzy fabric covering with either a solid rubber core or a hollow core filled with gas.
When the core is solid, the ball is called pressureless. When the core is hollow, it is filled with pressurized air or nitrogen so the balls are called pressurized. To increase the durability of both type of balls you can use equipment known as the tennis ball charger.
Now, below mentioned is the detailed comparison between 2 types of tennis balls:
- Delayed Bounce – Because pressurized tennis balls have a hollow core filled with pressurized gas, they will have more bounce than pressureless balls. Pressureless balls gain bounce when used as the felt wears away and the rubber softens.
- Spin Response – Pressurized tennis balls also have more spin response than pressureless tennis balls. However, the spin response, like the bounce of the pressurized ball, will decrease with time and use, as the pressurized gas in the core of the ball gradually diffuses through its rubber shell. Pressureless balls become more responsive to spin with use as their exterior felt covering wears away.
- Flight Speed – Pressurized balls have less mass than pressureless balls, so they travel faster. However, with age, pressurized balls will slow down, while pressureless balls will only get faster, as the slight drag from their felt covering diminishes with wear. The pressurized balls with decreased pressure are mostly used by beginners, as they will travel slower and bounce less.
- Jarring Impact – Pressureless tennis balls are heavier and harder than pressurized balls, so they impact the racket with more force. This is hard on the racket arm of the person hitting the ball.
Here is a great post to read on the topic that how tennis ball charger or saver is very much beneficial for tennis players.