I think a major area is that it specifically scans the registry in its scans, whilst avast has anti-spyware incorporated into it, it doesn’t specifically scan the registry.

Those with the Pro version would have that registry monitoring in real time and not just fo on-demand scans.

I thing one of its strongest features has to be rouge/fake security application detection, after all it started life as RogueRemover. You only have to look in the viruses and worms topic to see this.