On beta I played a Jedi Consular. Now I play a Sith Sorc.
Why? Because of those two abilities.
The tooltip on both reads "Instant", and they are equivalent spells as far as damage goes.
The primary difference?
With projectile you have to wait for the rocks to lift off the ground and then fly to your target before it does damage.
The second you press the ability it does damage.
It doesn't sound like much, but it can make or break a lot of fights, whether or not you get the kill before the person gets a heal off, etc.
Why is there such a massive imbalance between these two abilities?
That is a significant difference.
Do other classes have similar issues?