Dev team handles the...development and support. GMs, at least in the context we're using it here, handle the BT Invasions and special case on Dwilight. I think for the most part they handle story stuff, but also might have some role in maintaining proper atmosphere or something.
Also, the two spheres generally merge, so the Dev team for the most part knows who the story GMs are, or are some of them (Anaris was the Light in 4th Inv, for example)
Anyway, at least that's what I think is the case, basing this just on observations. In case anyone was curious, I'm unaffiliated with either group.
