Clones are exact or near-exact copies, usually being reversed engineered or based on licensed code.
The 6x86 incorporates several advanced architectural features that allow it to outperform a Pentium of equal clock speed. This was a good idea, to help people make more valid comparisons. Unfortunately however, it has caused a great deal of confusion of its own, because Cyrix named the chips with their P rating and not their clock speed. It is important to make sure that the chip is set to its correct clock speed. The branch prediction unit of the 6x86 can handle multiple branches and has better performance than the Pentium's.