On the Assassin chart you included a tab for "W/Exacting", but the Ranger equivalent is "W/Extra". What ability (or abilities) are being accounted for here?
Also take note on those cast times. Several Archer abilities have cast times of 2 or 3; most Assassin abilities are 0.5 to 1, making it easier to time with auto-attacks and not miss anything, or spam several abilities in the time it takes the Ranger to use 1.
And keep in mind that small differences in numbers for the hits can easily become big differences when ingame, after being modified by the 10 billion buffs and other modifiers.
No Ranger with Sniper Shot III will ever come close to what the Assassins are pulling off with Assassinate IV. It's a HUGE disparity.