Photon Fusion and Quantum are optimizing Unity with AAA features. Photon Realtime can work with pretty much everything but it will lack the features of Fusion and Quantum.
https://doc.photonengine.com/en-us/realtime/current/getting-started/realtime-int...
Fusion getting-started
https://doc.photonengine.com/en-us/fusion/current/getting-started/fusion-intro
Quantum 101
https://doc.photonengine.com/en-us/quantum/current/quantum-100/quantum-101
Fusion + Quantum samples
https://www.photonengine.com/en-us/samples
Quantum Free access form
https://doc.photonengine.com/en-us/quantum/current/multiplayer-game-jam/ggj-quan...
I hope it helps, thanks.
