It would be unreasonable to believe one twin could be 7 feet tall, and the other only 4 feet tall. Likewise with the tomato plants. The difference between the non-organic tomato and Glenn’s organic tomato would probably be a factor of genetics. Let’s say the non-organic gardener grows Early Girls. Early Girls are indeterminate, meaning that each branch forms three sets of leaves, then a flower cluster, then three more sets of leaves, then another flower cluster, and on and on. In theory, the length of each branch could be endless. (I have had indeterminate tomatoes grow to 9 feet!) Let’s say that Glenn on the other hand planted Romas, which are determinate. Determinate plants grow three sets of leaves and then a flower cluster, and then end.
In order for a determinate plant to produce another flower cluster, it sends out another branch from the base of the plant with another 3 sets of leaves and ends in another flower cluster. Therefore, a Roma tomato will never get more than about 2.5 to 3 feet tall, no matter how it is fertilized. Which brings up another trait of tomatoes. If a tomato plant gets ample fertilizer, it remains in a vegetative state, producing few tomatoes. If the plant however receives little or no fertilizer, and reduced water in the latter part of the summer, it shocks (or stimulates) the plant into the reproductive stage of producing fruit. If it were me, I would cease any type of fertilization, organic or inorganic, after the plant gets off to a good start in the spring.
I beleive genetics can play the biggest role here, but also consider a few other factors…did the inorg, buy his plants at the local store? Or grow them from seed?, are they in full sun or reaching for the sky due to shade or close planting. Does he have a cold fram or other heated structure? I beleive that heat really is the biggest determining factor for quick growth, an example would be growing up against an east wall that gets a lot of sun vs a north wall that does not. Sounds to me like the inorg is a braggart anyway, the real proof is in how good the produce is….do they have ANY flavor?