How do the littoral zone and the benthic zone differ?
The littoral zone is the part of a body of water that is near the shore, while the benthic zone is the deepest area of a body of water, including some of the sediment.
There is some debate about the exact definitions of these terms and they are not always used in the same way. But generally, the littoral zone includes part of the shore, the intertidal zone, and some of the shallow parts of the body of water (except for the ocean, where the littoral zone can be considered much larger). The littoral zone is inhabited by many species, examples include crabs, sea urchins, and many plants.
The benthic zone is the deepest part of the body of water, and actually can overlap with the littoral zone. For example, a few feet from the shore of a lake, the sediment can be considered to be in both the benthic and littoral zone. But when you consider the sediment in the deepest area, that would be the benthic zone only. Benthic organisms vary dramatically based on what body of water you are looking at, but in the ocean, you can find lots of echinoderms (like sea stars), jellyfish, and some fish.
Here is an image of a lake that shows some of the zones: