Relationship between the and the ember-cli websites

It is my understanding that ember-cli is part of emberjs. Given this, why is there a separate website? What does it provide not covered by

Also, the user guides at recommend different versions of the prerequisite JS packages than For example, for Node, recommends version 0.12 or higher while recommends version 4.0.x or higher.

I’m new to Ember and just trying to figure things out a bit.