There's a difference for us in my town (Canberra). Our police are federal, not state. So they aren't too fussed about collecting fines for the local government. Generally police with hand-held radars will allow 10% above the limit before they start pulling you over.
We have fixed cameras, which have lower tolerances, as well as white vans. I think part of the strategy is that they are high visibility in 'high risk' areas, thus forcing the traffic to slow (and not 'ambush' them).
In the Australian States (such as Victoria), they are much more strict...
Here's one of our vans....very high visibility on purpose: