Hosts File vs. Block Lists

Will enabling the Spybot SD host file overwrite IESpyad's block list, or will it just add any possible entries that SD doesn't have? Also, is a host file and a block list the same?

 

Hi. I thought IESpyAD adds bad sites to your restricted zone in the registry. SD adds entries to your hosts file, and immunize sets killbits in your registry like Spywareblaster . I sure someone here can give a better explanation.