Bigport has big intake ports, which lack flow velocity down low and has TVIS on it to improve this along with an 8 runner intake manifold, they have 240 deg cams and the block has 9.4:1 compression.
Smallport has smaller intake ports, they have a better flow characteristic and use 4 runner intake manifold, they have 232 deg cams and the block has 10.3:1 compression along with oil squirters.
There are probably other things I have missed, but that's the jist of them.