Differences between anger and rage Can rage be considered a subset of anger or possibly a separate neurobiological process.

What are the neurobiological, evolutionary and psychological differences between anger and rage? 

In more detail an examination of the similarities and differences between anger and rage, their roles and purposes for us as a species.


what is the difference in neurochemistry   
what are the evolutionary advantages of these states. 
how do these two neurochemical processes assist us psychologically with regard to survival of our species 


An examination of misplaced anger or rage, as possibly less useful states, although perhaps not entirely redundant, and possible pathology arising from this may or may not be included within answers.
The American Psychological Association appears to view this emotion as a continuum of intensity, whith annoyance at the mild and rage at the extreme end.

http://www.apa.org/topics/anger/control.aspx

Excessive anger and rage might be caused by suppressing milder forms of anger until this repression becomes unbearable and "the pot cooks over". Psychology Today calls anger a "corrosive emotion": it eats away at you, if you don't express it.

http://www.psychologytoday.com/basics/anger

The continuum and boiling-over idea of anger are nicely summed up in this paragraph of another Psychology Today article:


  Irritation, frustration, anger, rage: these are all forms of anger. And they are feelings first. But when a person’s rage becomes behavior even before thought has a chance to plug in, it is usually because of one of two reasons:  1) it’s been repressed for a long time, and when someone drops the proverbial straw, it explodes; 2) it works for manipulative purposes.


http://www.psychologytoday.com/blog/traversing-the-inner-terrain/201205/is-rage-choice