One could be like the halo CE/ halo 3 with a slower fire rate, zoom smaller clip and more powerful bullet. the other should be like the halo 2/ODST/reach with faster fire rate larger clip no zoom less powerful bullet and a slightly faster kill time at max fate of fire.
While I think this is a good idea and definitely do-able, I don’t think we would see something like this happen, especially after what we saw with the plasma rifle and the plasma repeater in Reach, but I could be wrong.