Answer:
Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lack soil.
Secondary succession is one of the two types of ecological succession of a plant's life. It is the process started by an event (e.g. forest fire, harvesting, hurricane, etc.) that reduces an already established ecosystem (e.g. a forest or a wheat field) to a smaller population of species, and as such secondary succession occurs on preexisting soil whereas primary succession usually occurs in a place lacking soil.
Explanation:
Primary succession takes time for completion around 1000 years, whereas secondary succession area takes 200 years for completion. In primary succession, there is a lack of soil and humus for the sustaining of life whereas, in secondary succession, soil and humus are present with some organisms.
A Secondary succession can take a few hundred years.
