1. Ecological succession is how biological communities change, re-structure and re-assemble over time, usually after some change or disturbance, or occupation of a new habitat. Ecological succession usually starts with a very simplistic structure, with some founder species that begin, then over time (it could be 10 years, it could be millions of years), the population grows in complexity and develops.
2. Exponential growth refers to a specific pattern of growth that occurs when resources are not limited. This pattern is when the size of the population is always increasing at a greater and greater rate. The best example is in bacteria. When they are in favourable conditions, the cells keep dividing, doubling every day, leading to exponential growth until nutrients become limited and growth slows.
