I just cant think of anything that would be different in their environment. Soil was all mixed together before potting, all nutes have been exactly the same, and they are all equal distance from a 600w HPS light. The shorter ones are on stands so they are all equal, if anything they are over...
I have 4 dwarf low flyers about 2 weeks into flower. They all look great but each one seems to be a very different plant than the other one. One is over 4 1/2 feet tall and kind of stretched looking, another is 18 inches tall and looks like a big bush. The other 2 are in the middle somewhere...