Yes, akermann is the turning difference of the outside versus inside tire.
The below is just my impression, the actual facts could differ. 
When I say steering aggression, I'm referring to the arc the toe links take on the servo. With the servo flat, the outside wheel's tie rod inner ball is going down. That means, with the same speed servo and all other things being equal, the initial steering speed off center is quick, and is then slowing down, and the inside wheel is turning at a fairly constant rate.
With the servo angled, the outside toe link is rising, so the initial turning speed is a bit slower, but finishes turning more aggressive. The inside wheel can get to a point where it just stops turning while the outside still has some turning angle left to go, in certain configurations, usually with a lot of akermann apparent.
Of course, there's exceptions, special cases and a lot of variables that can change everything all around as well. Depending on the chassis and front end you're running, it's still trial and error, with a handful of shims to see if you can get exactly what you want.