I'm gonna start with the basics then move on from there.

-Run of the mill average Joe in the zombie world.
-Slow and easy to avoid.
-Like all infected a strike to the head does the trick. (no where specific, just hit the head)
-Powerful in numbers.
-The Front Linesmen of the Zombie Army.

-Quick, fast and really fucking annoying.
-The cause for most wounds, aka they hit really fucking hard.
-Seem smarter then the rest, small groups tend to flank whatever the main horde is attacking.
-Often stick in packs of 10-15, slower ones usually never travel with them.
-Will never run around when they aren't in pursuit of a target.
-You have stamina, they don't.

-Frail and weak, most move as if they can't support their own weight.
-Always run, I am unsure as to why this is.
-Attack quicker then most Adult runners.
-Unpredictable.
-More likely to be with female infected then males.