I'm pretty sure this isn't the case. The design of the stems appear identical to me.
Agreed, I knew the stems are identical (thank you, ripster's images) but what I said earlier was because I do feel that the actuation seems to comes faster with my greens, which may purely subjective; because of the stiffer springs in the greens, I tend to feel less key travel before actuation because I'm pressing with more force and less control. While on the blues, because of the lighter springs, I can more easily control how much strength I put into my key press. I guess I should have clarified
For the sake of rough keyboard science, I just got out a ruler and roughly measured the key travel before actuation on both keyboards and I observed that there is about 2mm travel on my blues before actuation, and similarly for the green about 2mm. Can't say for exact but take it for what it is