I could be wrong but I think the easiest way to spot the difference is to check the shade mark on the fdl at the 10 o'clock position.

Of course I never noticed the difference. Therefore I need several colors.

I'm pretty sure no one has the green besides Roy and myself. I would trade a green for one I need

In the scan below the yellow and red are one type (shade on left side of 10 o'clock fdl). The other 5 colors has the shade on the right side of the 10 o'clock fdl

Trade anyone?