Difference between Men's and Women's Tennis balls?

Question

While watching the 2022 US Open 1st Round match between Raducanu and Cornet, one of the commentators said something along the lines of the following:

[...] the balls are different this year, they are slightly heavier than before, but still different to the men's balls.

^{Not exact wording, it's from memory, but the gist of the sentence is the same.}

This surprised me as a very casual tennis fan, in that I naively assumed that a tennis ball is pretty much the same as any other tennis ball and, if there are differences, then at the elite level I would have thought that there would have been some standardisation across the professional scene, for both men and women.

What are differences between the men's and women's tennis balls (if any; perhaps I misheard the commentator, or he misspoke), and why are they different?

Answer 1

The ITF has several different tennis ball types that it permits. Each tournament can choose which balls to use from any that meet the qualifications. The USTA publishes a list of approved balls based on the ITF standard that are approved in USTA tournaments, including "US Open" balls.

The US Open is the only Grand Slam that uses different balls for Mens and Womens:

While the men use Wilson’s US Open extra duty balls, women use Wilson US Open regular duty balls which are enveloped by a thinner and less fluffy felt cover, leading to a faster, more aerodynamic ball, and consternation among some players.

The effect may be to speed up the game some, though that is controversial as a lighter ball will be faster initially but then slow as it has less momentum.

The stated reason, however, is to reduce injury:

"The WTA has always utilized regular felt balls for hardcourt play, and we have now begun to hear from a select number of our athletes that they would like to consider a change to using the extra duty ball," Binder said. "The basis behind using the regular felt ball was that it limited the potential of arm, shoulder, elbow and wrist injuries. This is something that we will continue to monitor and discuss further with both our athletes and our sports science teams."

Answer 2

This is a somewhat controversial decision taken by the US Open to deliberately use different balls for men and women. Quoting from this iNews article:

While the men play with Wilson’s extra duty tennis balls – developed specifically for hard courts – the women play with regular duty balls, which play faster, are less durable and are actually more suited to softer surfaces like clay or indoor courts.

At the other Grand Slams, it is as you expect and the men and women use the same ball.