Final answer:
Primary succession is the soil formation process on new land, beginning with pioneer species, while secondary succession occurs on pre-existing soil with faster recovery due to existing soil nutrients.
Step-by-step explanation:
The major difference between primary and secondary succession is that primary succession involves the formation of soil, while secondary succession occurs in areas where soil already exists. Primary succession occurs on newly exposed or formed land, such as after a volcanic eruption or a glacier's retreat, where there is no pre-existing soil. This process begins with the weathering of rock and the establishment of pioneer species, like lichens and some hardy plants, which help in soil creation. In contrast, secondary succession happens in areas that were previously occupied by living organisms and where the soil is already present, such as after a fire, flood, or human activities like farming. Subsequent growth is facilitated by the remaining soil nutrients, making secondary succession typically faster than primary succession.