There is no difference whatsoever between 96 and 97.
Between 95 and 96 the heads, intake manifold, and exhaust manifolds all changed. The exhaust manifolds became tubular headers and the intake manifold was designed to accept fewer (12 as opposed to 14) and smaller bolts. There were also a lot of changes in the sensors that were used. All 96+ engines were OBDII where as earlier engines were OBDI. As far as internal differences (cam, crank, block, etc.) I do not know.