I get the feeling both were designed / organised 'in house' - although I'm not sure. But I've always found HMRC far more user-friendly than other government sites. It's when they farm stuff out to the likes of Crapita that it all goes wrong.
It will be interesting to see how this works (if at all) for local authorities. We have a grant from government of around £5m, which is only around 50% of what we need to function. The other £5m we make through commercial things things like car parks, cafes, information centre shops, boat...