How about I tell you the difference?
EO is a place for Eldar, Dark Eldar, Harlie, and Exo players... We have tried, for the past two years to make the largest and most informative community for these players.
Due to the popularity of EO, many of our members have requested that we do the same for all the other races. That said, it would be a very ambitious goal to try to make EO for all the other sites, but we believe that with the help of many of our members, that we can do this. Since then, we've opened up 40k.ca's forums and it's booming already even without a website. The website shall be coming soon - we're waiting on some software that would help the site run a lot smoother.
We already have several cool projects for EO and we're working on them constantly. Hopefully soon we'll have a website out. 40k.ca will always be a work in progress because there is an endless amount of content we would want to have on the site.
I look forward to having everyone contribute their talents after the site is up.
I hope that answers your question.