In general Status moves have a 3 second effect duration buff. Typically 15s > 18s or 30s > 33s. Other moves simply get a decreased wind-up time, like Aqua Ring (since its effect lasts forever already).
In the case of Protect, its Cooldown time is reduced from 15s to 12s. Detect's is 13s > 10s.
Posting this as a comment because I cannot find the effect this has on status inflicting moves like Confuse Ray, hazards like Toxic Spikes, and I'm unsure if Protect+ has a stronger effect on Plus attacks which normally bypass protection.
It seems like this is the extent of it but I'm not confident enough to assume that GameFreak would overlook these things? Why give the player the option to waste their Mega Meter for no reason?