> The difference comes in the form and variety of scenarios.
The difference is that one is real, whereas the other is simulated. It is very hard indeed often impossible to perfectly simulate the actual use of a system. Thus the simulation will be incomplete, and quite possibly in fundamental ways that aren't appreciated until problems occur. It doesn't matter how many tests there are or long they are run for - they can only be at best an indication of how the system will actually behave when confronted by its 'battle' environment.
I agree. Rocket science is a good analogy here, there is no way to simulate space, on the other hand there are a number of smart checks you can do when a rocket is updated before putting it back on the launchpad.
The difference is that one is real, whereas the other is simulated. It is very hard indeed often impossible to perfectly simulate the actual use of a system. Thus the simulation will be incomplete, and quite possibly in fundamental ways that aren't appreciated until problems occur. It doesn't matter how many tests there are or long they are run for - they can only be at best an indication of how the system will actually behave when confronted by its 'battle' environment.