SBPRO.DRV is always for OPL3. The only OPL3 feature it uses is stereo panning; it still uses only 9 channels and two-operator instruments.
What Sound Blaster drivers support which cards?
AUDBLAST.DRV automatically detects 16-bit and Pro cards and utilizes those features, at least the driver that comes with those later games that actually provide 16-bit recordings. And for those earlier games that only provide 8-bit recordings, the support for the advanced cards is dispensable anyway.