Ecosystem is a community of living and non-living things working together. Ecosystems have no particular size or location. Generally, we classify ecosystems based on how they are created. The natural ecosystems are the type of ecosystems where it is found in nature. It has been there and evolved as the time pass by. Examples of natural ecosystems are forests, deserts, seas and many more. Man-made ecosystems are the artificial ecosystems made by man. Examples of which are farmland, aquariums, terrariums, gardens, ponds, and many more.
Biodiversity defines as the variation of species in an ecosystem. We can say that natural ecosystems have more biodiversities (or complexities in number of species) than the man-made ones. It is because man made ecosystems are limited to what the creator wants for his ecosystem.