Are other lab grown gemstones made with roughly the same HPHT process? I ended up getting a diamond from Gemesis for my wife years ago, this is a very fascinating topic for us.
Outside of the growth cell, the machine and environment also influence growth. Temperature and pressure ranges, tolerances and gradients of the press all factor in to the final quality of the diamond. Ambient room temperature and humidity as well as conditions during the growth cell preparation play a role too.
For consumers though, when considering two 1.0ct G color, VS2 clarity round polished diamonds (for example), it doesn't really matter what process it came from, who grew it or what size or shape the rough diamond was.