Oh wow, this is the first MMO that I've played that crit hit rate and chance is different. or maybe the term is just too confusing
http://i.imgur.com/8rUhDko.gif
Edit:
On another note, I tried using the simulator in the link, and checked Internal Release and pressed Calculate, and it does increase Critical Hit Chance.
Internal Release description is Increase Critical Hit Rate by 20% and going by the link you've posted, it does increase the Critical Hit Chance, so Critical Hit Rate = Critical Hit Chance.