Carnivores are organisms that eat meat and meat only. Omnivores are organisms that can eat both meat and plants. Producers are organisms that are able to produce their own energy, such as plants or any organism that is capable of photosynthesis. An omnivore can theoretically consume both a producer and carnivore while a carnivore can, theoretically. only consume an omnivore, but a producer heavily relies on sunlight for energy.
Irrelevant info dump:
Of course this isn’t wholly accurate as there are still some unknown species out there, but typically the first thing many people think of when speaking about carnivores would be a lion or hyena. There are also carnivores plants out there which is really fascinating, but isn’t relevant.
We, humans, would be considered omnivores. There are vegetarians out there, aka herbivores, but that is by choice.