Breez does local side routing so it’s sometimes a bit slower, but because it’s more private. It’s running basically a full neutrino light node on the phone.
In a nutshell: Breez is slightly more sovereign, Phoenix is slightly more responsive.
Discussion
Should also consider the fact that Breez will integrate Greenlight of #[5] and anyone will be able to spin up a self-custodial node in the cloud without having to deal with all the technical details. Really powerful