Similarities
Ecosystems and biomes differ, but they both serve a common purpose. The two systems are closely linked to provide support for life on the planet. Ecosystems are integrated within biomes, much like subcategories are found in a list. Ultimately, they allow humans to draw lines between different environmental and ecological systems.
Size
Since biomes contain a variety of ecosystems, this naturally means that ecosystems are smaller. They are limited to certain groups of animals in specific environments. Biomes, on the other hand, encompass a broader range of life and territory. According to M. Lynne Corn of the Environment and Natural Resources Policy Division, a biome "is the largest geographical biotic unit, and is named after the dominant type of life form..." In short, you identify a biome by its most common organism. The "dominant" life forms in a biome usually involve certain native plant species. As a result, biomes are named after the environment, such as the grassland biome or rain forest biome.
Biodiversity
Unlike biomes, ecosystems are not identified based on the most prominent life form. This makes them very difficult to categorize. Many ecosystems contain a mixture of animals that find their way to other ecosystems. In some cases, ecosystems are destabilized by species that do not belong there. Biomes, on the other hand, encompass all the animals, plants and environmental characteristics like temperature or rainfall in the region. As a result, biomes cannot be upset by invasive species or changes in a few of their ecosystems.
Function
Ecosystems and biomes serve different purposes. Ecosystems serve to indicate the transfer or flow of energy throughout the system. For example, an ecosystem shows where animals get their energy for survival. Some animals eat plants while other animals eat each other in a process called the food chain. Research into biomes focuses more on the most common living organisms than the interaction between all life. The grassland biome, for instance, is known for its small, slow-growing grass, flowers and other tiny plant life.