Guild Wars 2

Is there a difference? I know precision contributes to crit (I think 21 = 1) but is there any other difference, such as the crit increase modifier or something?

Crit is more than likely critical damage, unless it explicitly says critical chance. Base crit damage is 150, and any extra damage over that is additive to the base, i.e 30 crit damage gives a total of 180% critical damage.

At level 80, critical chance formula is ((Precision-916)/21)+4.