Maybe ENT provided a final hint on this issue:
The NX-01 Enterprise did not have any shields/forcefield technology at all. The only defense seemed to be polarized hull plating, which could be energized as a defense.
Look at it this way: "screens" or "deflectors" would be the outer layer of defense, an relatively high-energy layer comprised of overlapping forcefields. "Shields" would be the inner-most layer, comprised of polarized hull plating and maybe an intermediate forcefield.