Hey, plant 1 (wedding cake auto) is 7 weeks old and exploding. The 2nd plant (Purple Queen auto) is also 7 weeks old but much smaller. What's up with that? Both were done with LST technique.
No diary = no information. In general, though, I would simply put this down to genetics... different strains, even different seeds of the same strain, will not be the same height - they're individuals.