last edited by AmbivalentDuck
The huge difference is +1 damage. If you Gempalm on turn 2, you're not usually getting your Lackey past a typical Vintage turn 1-2 blocker. Being able to turn 1 Lackey, turn 2 this and actually get to use your lackey is a big deal. Consider that Gempalm doesn't even kill Baby Jace in its 0/2 form until after the block.
Also, and I know it hasn't been widely adopted yet, but this can hit Karn directly. I strongly suspect that Karn the Great Creator is secretly the most broken card in Vintage right now as it shuts down multiple archetypes game 1 either directly with its passive or indirectly by fetching a silver bullet. Unlike Jace's 0, which might or might not find something great, Karn finds things like Tormod's Crypt, Ensnaring Bridge, and Trinisphere with 100% accuracy. They aren't usually worth maindecking, but they can be absolutely brutal out of the sideboard. To take advantage of it, I think you just want something like Legacy 8 Moon with more Goblins and Karns and less Chandras.