Difference between "-march=k6-3" and "-march=k6-2"?

[Steve Snyder]

In GCC v3.2.x, what is the difference in code generation between the 
"-march=k6-3" and "-march=k6-2" options?

My understanding is that the only difference between these CPUs is that 
the K6-3 has an L2 cache, where the K6-2 does not.  Is the difference 
between these -march option just exploiting that cache, or is there more 
to the code generation than that?

Thanks.