"Microevolution" vs. "macroevolution."

OK , I'm going to second Subbie's original question, what is the difference between microevolution and macroevolution? I see it as the definitional difference between micro and macro or the same principles expressed on different scales.The analogy would be economics. Microeconomics is on the scale of the individual and Macroeconmics is on the scale of the group. The same patterns / models are applicable on each scale.I would contrast this to what I think is generally called "emergent properties" where differences of scale result in observations of small scale that do not explain observations on the larger scale.A crude example of this might be stellar fusion where the behavior of even a large quantity of Hydrogen would be explained by gas laws until a critical level is reached and then we have an entirely new behavior where the hydrogen ceases to be itself and becomes Helium.Is there a critical limit at which Micro becomes Macro or is it just a convenience of observational terminology?

I agree that behavior is an emergent property of cellular function, at least in general, but I don't think that clarifies Micro/Macro. I'm more with Jar in this sense, If you did have a complete set of intermediates, you would only be able to define arbitrary breakpoints between them and the sum would be Macro but the individual changes would be Micro.As with species, I think the distinction is only really there in terms of convenience of categorization.