The procedural difference
The most consequential difference between Scottish and English building control is not technical. It is when approval has to exist.
In Scotland, a building warrant must be applied for and granted by the local authority verifier before work starts. There is no equivalent of the English building notice route, under which construction can begin and details can follow.
Why that changes the design programme
If approval must precede construction, the design information supporting it must precede construction too. A services design that would be developed through the early construction period on an English project has to be substantially complete before a Scottish project can begin on site.
This is routinely underestimated when a design team accustomed to English procedure takes on Scottish work. The programme is not the same programme with an extra form in it.
Completion certificates
The second procedural difference sits at the other end. A Scottish building cannot be occupied until the local authority has accepted a completion certificate, which puts commissioning records, test certificates and as-fitted information directly on the critical path to occupation rather than trailing behind it.
Where England is converging
The Building Safety Act 2022 gateway regime, which applies to higher-risk buildings in England, requires approval from the Building Safety Regulator before construction starts — much closer to the Scottish model than to the traditional English one. For those buildings, the two jurisdictions now behave more alike than they used to.