To the human eye, both are quite bright. You might notice a difference if you had a Ray2 and a Fugeray next to each other, but both provide plenty of light.
Another comparison: the Marineland Double Brights are noticeably dimmer than the FugeRay.
If you have no lid over your 40B, get a FugeRay.
If you do have a lid, get a Ray2.
Both will give you plenty of light, CO2 or not.