Anyone have a good understanding of the difference between this and http://www.dotnetdotcom.org/ http://www.dotnetdotcom.org/? I've seen Dotbot in my access log

Anyone have a good understanding of the difference between this and http://www.dotnetdotcom.org/ http://www.dotnetdotcom.org/? I've seen Dotbot in my access logs more than CommonCrawl, so I'm more inclined to believe they have a wider - but not deeper - spread.