One is simply the other over longer time scales -- not a different mechanism.
I would argue that generational changes can occur within a species that aren't necessarily the road to a new species a million years down the road. In that case, micro, at the very least, can be different from macro. As I posted previously, I don't have access to my notes at work but my recollection is that different causes have been proposed for both micro and macro changes. In the latter case, two I recall are adaptive radiation and successive speciation. It is my understanding that while successive speciation might be an example of micro evolution at the macro level (as you suggest), adaptive radiation is a different mechanism. Again, this is all without notes (or a net) so my recollection may be incorrect.