Microevolution is the small-scale change in the frequency of genetic traits in a population over a short period of time. This change can be caused by a variety of factors such as natural selection, genetic drift, and gene flow. Microevolution can lead to the formation of new species over time, but the process occurs over many generations and is sometimes difficult to observe.
Macroevolution is the large-scale evolution that occurs over a long period of time and can involve the emergence of new species. Macroevolution is believed to occur over millions of years, and it can be observed in the fossil record or seen in the presence of new species in the present. Macroevolution is thought to be driven by the same factors as microevolution, but on a much larger scale.