They're different champions. It's not really a fair comparison.
In any case, remember that both Ezreal and Ahri have to be within a certain range for these targeted projectiles to fire. Ezreal's range is extended by the blink portion of the skill, while Ahri's does not have that built-in extension. She can ult to close the distance and get in range, but that costs an additional chunk of mana and/or a charge.
Despite the slightly different mechanics, both abilities function in essentially the same way. If you activate it from too far away, it will fail to hit your intended target due to acquiring a different one. Both champions must be within a given range in order to hit their target.