In a nutshell and imho:
Bass = FX40 wins
Sub bass extension = FX40 wins
lower mids = GR02 wins
Upper mids = GR02 wins
Highs = FX40 and GR02 draws
3D like staging = Definately GR02 wins
Price/performance ratio = FX40 wins
Cables/Micronics = Draw
Both earphones are at their best when listerning in a quiet place i.e at night.
Both have a fun sound signature that's clear in all the necessary areas and both are excellent as a first IEM for anyone starting on this journey.