If you reload for both, the 30-06 will provide 150-200 fps more velocity than the 308. To me in the field, the difference is not important but for the sake of pure numbers, the 30-06 has a bit more powder space and will always have a bit of an edge. If you like the short action better use the 308. If you prefer a little more velocity from heavier bullets and don't mind the longer action, the 30-06 is for you.