Macro-evolution and micro-evolution are terms sometimes used in a scientific context, but more often thrown around by creationists to get around some of the instances in which evolution has been observed. "Macro-evolution" means evolution on a large scale, while "micro-evolution" means evolution on a small scale. A common creationist claim is that micro-evolution has been observed, but macro-evolution never has.
In science, however, there is no clear dividing line between the two. To the extent that "micro-evolution" is a recognized term at all, it generally means change within species, while macro-evolution means change between species. Unfortunately for creationists, speciation has been observed in laboratory conditions -- scientists have successfully induced the evolution of new species that cannot breed with the original strains.
While it is obviously the case that nothing can be directly observed when it occurs on a large enough scale (i.e., longer than a human lifetime), macro-evolution is well confirmed through various tests and models.
Because speciation is an observed phenomenon, creationists like to redefine terms by talking about "macro-evolution" not in terms of species but in terms of "kinds." But a kind is not a scientific notion, and creationists are notoriously vague when it comes to defining what it means.
- For instance, is a chihuahua the same kind as a Saint Bernard?
- How about a chihuahua and a dire wolf?
- How about a wolf and a house cat? They're both mammals and both in the carnivora family.
In science, there is no clear dividing line between "kinds" beyond species (and even species can be a fuzzy term). Creationists do not agree with one another about exactly what "kind" means, either, and have never proposed a rigorous definition. They only agree on the ad hoc sense that whenever it can be agreed that evolution is solidly proved between two species, they must not be the same kind. This is an example of moving the goalposts.