All that is a question of terminology. The classic terminology is mitigation opposed to avoidance. Mitigation being fixed and resulting mainly from armor and stance, and avoidance being statistical and resulting mainly from dodge, parry and misses. I know.
But while I'm not that familiar with english, I have a clear conception, though not original at all, where I distinguishes :
1) what is usually called "mitigation", that I like to call "fixed mitigation" (and part of EH because you can rely on it)
2) what is usually called "avoidance", that I prefer include in a wider and IMO more relevant concept called "statistical mitigation" including as well block and other variables that tend to stastically provide a sort of mitigation (but not reliable, unless huge iterations).
3) the combination of the two types of mitigations, fixed and statistical, called "global mitigation"
I had that conception before knowing about Rawr, but I see that Rawr has a quite similar conception, and calls "total mitigation" what I just called "global mitigation", what is the same to me. As far as I remember, Whithetooth calls it "total damage reduction" or something like it in Tantpoints. So I think it's a relevant conception, maybe more relevant than the three classical concept alone : "EH", "mitigation", "avoidance".
Why ? Because IMO there is two major relevant concepts when thinking about survivability, being "EH" and "global mitigation" (or "total"), that deserve two different goals or logics : surviving some huge bursts for "EH" and being economic to heal for "global mitigation". And one step under, when thinking about "global mitigation", there is again two major logics : what is fixed, constant and you can rely on, and what is only statistical, variable, and you can expect but not rely on. Avoidance is just part of the second logic, but not all. Unless you're unhittable, and even if you're, because of critical blocks and block mastery, glyphs etc, block is variable and necesseraly a "statistical mitigation". If you go further, you can also put the effect of expertise against bosses that have still parry-haste in that category, along with a lot of proc "including Aegis of Black Heart, that is no real "fixed mitigation" and "EH" as it's not truely relyable). This division between what is relyable and what is not is usefull, as it open to a clear conception of EH : "HP" increased by "fixed mitigation".
Well, I hope you see what I meant, it's not just easy trolling. But I agree that my terms are or could be confusing, and it was the very reason why I tried to sum up the idea briefly in parenthesis hehe. Anyway, if you have suggestions about terms more relevant in good english, I would be elated.