The Pentium® II processor core represented a slightly modified Pentium® Pro processor core. It has the following differences:
The L1 Code and Data Cache sizes were increased in size from 8KB each to 16KB each.
While the Pentium® Pro included ECC protection on both the L1 and L2 Caches, the early versions of the Pentium® II did not have ECC protection on the L2 cache. The later versions added it back in.
The Pentium® Pro did not exhibit optimal performance when executing legacy 16-bit code. The Pentium® II corrected this problem ...