Also the water pump, crank (oil pump drive), and oil pump were changed in 86 on all CVH engines to a different type. Late S2 blocks also were of the EFI type with readily machined locations for a crank position sensor and and a knock sensor.
Actually there are quite a few differences, but none of them make one or the other better in any way. The differences in the head and valve-gear are also very marginal.