It’s a different way of routing audio through the system. For the average user it won’t make a whole lot of difference, but for some (you and I, obviously), it provides a bit more control over the flow and its performance. Very useful when doing things such as recording in a DAW.

Unless this is something a user needs to care about, there will be no noticeable difference. Pavucontrol is still an excellent front end, even if the back end is handled by pipewire.

EDIT: Yeah, now that I think about it, like that other guy said: Bluetooth audio. It got more or less trouble free after I switched to pipewire a while back on my Mint 21 machine.