It does stuff the old Pedalboard doesnn't do, like amp capture and vocal effects. Also features Revalver software, an emulation developed previously for Pea ey, if I'm not mistaken.
Also has new graphics for amps and effects, WiFi and Bluetooth audio.
For me the coolest this is that it can use old PB user banks, making the transition easier for previous HR users.
This kinda sums it up.
I own both a Line 6 Helix and a Headrush MX5, but the Prime just doesn't isn't for me. But it looks and sounds like a grest piece of kit for anyone looking for a good amp emulator / MFX board.