What makes a commercial camera system different from a residential one?
Three things, mostly: how long you keep footage, who needs access, and what the cameras have to be able to prove.
A home system that keeps a week of footage is usually fine, because you know within a day or two if something happened. A business often finds out weeks later, during an audit, a chargeback dispute, or an insurance claim. If the recorder has already overwritten the window, the system did nothing for you.
Commercial systems also need resolution and placement good enough to identify a person, not just record that someone was present. That's a design decision made before anything gets mounted.