I don't know whether I should post as I haven't flown in a FBW Airbus except for jump-seat rides and a couple of gash circuits in a sim years ago...
I think the biggest differences are not in the FBW systems themselves but in the pilot interfaces. A(irbus) have gone for low-feedback 'attitude demand' and B(oeing) have stayed (partly) with conventional controls and responses.
The 'control laws' in the B stay relatively constant but change with proximity to the ground in the A.
The B has a synthetic 'trim' to make people feel at home but removes the need to coordinate turns with the elevator up to 30degs AOB. It also removes the pitch couple from using engines, flaps, speedbrakes (not very well) and gear.
They both have a myriad of 'protections', the difference being the B's can be overridden by firm use of the controls or by disengaging the autopilots.
Both A & B have degraded 'fallback' control modes as the computers fail one by one... I don't know about the A but the B gets nicer to fly as bits fall off! (Electronically speaking)
Different ways to skin the cat but you end up with a feline sans epidermis at the end...