How is primary succession differs secondary succession?

starting materials

Remains of organic materials , seeds etc .

Secondary sucession is the sucession that happens after an environment grew and after something happened to it. Primary sucession is an environment that started out new.

Primary comes from nothing and secondary comes from a previous community.

They both taking along time period to form the forest back. Primary approximately thousands of year because they started from an empty land. Secondary approximately only take hundreds of years...