The difference would be the factors (biotic or abiotic) which are included in each level of organization.
First let’s review biotic and abiotic factors.
Biotic factors are living organisms an example would be a deer.Abiotic factors are non-living objects an example would be the air.
Population – All the members of one that live in a defined area.
Community – All the different species that live together in an area.
Ecosystem – All the living and non-living components of an area.
Here is a video to help with this concept.

Hope this helps!