The single most common question vegetarians and vegans get is "Where do you get your protein?" There is an obvious answer, and as with most things regarding food that answer is scattered, smothered, covered and chunked with everything from boring science to outright propaganda. The short answer is that they get their protein from the food they eat, because all food is made up of some combination of three things: protein, fat, and carbohydrate.
A related question is usually along the lines of, "So you have to eat weird spongy bricks floating in water, or mushy beans all the time?" Nope. Fruits and vegetables have protein. Broccoli, spinach, peanuts, figs, sunflower seeds, potatoes, strawberries, corn, avocado, peppers, barley, cabbage, and any plant you can name all have protein. A person who only eats plants (fruits and vegetables), can get enough protein without even thinking about it. Still not convinced? Have you ever seen a bull? Over two thousand pounds of muscle and bone, and it all came from plants.
But, like an omnivore, a vegetarian who eats junk food will be unhealthy. "What's an omnivore?" or, more disturbingly, but sadly not more uncommon, is the follow up question, "You still eat chicken, right?"
So, here's a list of diets and their definitions.
Carnivore: Eats animals almost exclusively. Cows, pigs, chickens, fish, sheep, snails, crickets. If you want a cheat sheet, you can remember the basic tenet that if it has eyes it's meat, but that's not foolproof. Best to go back to the tree of life classification systems from your Kings Play Chess On Fine Green Sand high school biology to really understand what an 'animal' is. Fun fact: some animals, like cats, are obligate carnivores, meaning they couldn't survive on a vegetarian diet even if they wanted to.
Omnivore: Eats a combination of animals and plants. This would seem to be the diet with the widest range of food choices, but oddly, in my personal experience and my observations of what other people eat, most omnivores are really carnivores with the exception of small amounts of potatoes (french fries) and corn (breading) added. Fun fact from The Omnivore's Dilemma: Chicken McNuggets contain more corn than chicken.
Pescetarian: Eats plants, but also fish. Sometimes wrongly classified as a type of vegetarian, hence the combination of pesce- meaning fish, and -tarian, as if to imply vegetarianism, but, no. Fish are animals. Possibly the mistake came from the pre-Nemo era, when fish were not considered cute enough to be animals.
Now things get murky, and the eye-rolling, defensiveness, name-calling and fear-mongering really begin. Introducing the VEGETARIANS!
Lacto-ovo Vegetarians: As sexy as the name is you'd think it was going to be special. Nope, eats plants, but also eats dairy products and eggs. You can subdivide these categories further into lacto only or ovo only, but the division is usually based on allergies or taste preference.
Whole Food Plant Based Vegetarians WFPB: Eats plants. No dairy or eggs. This category is sometimes further restricted by allowing no oil (no means no. No coconut, no olive, no fun). The focus of the WFPB diet is on foods that are minimally processed. The diet is designed for health and the components of the diet have been vetted by numerous scientific studies. It is a de facto vegan diet, but it should be distinguished from the practice of veganism, which encompasses more than nutrition, as described below.
Vegan: Often considered the strictest diet, although it's not a diet at all, but a lifestyle choice. (However, if you are just comparing the diet aspect, WFPB-no-oil has more limited choices than a vegan diet. Example: oreos) The basis of veganism is to completely avoid consumption or use of any product derived from an animal. Vegans don't eat any animal products, including honey (bee slave labor). Vegans don't wear leather or silk coats or shoes, they don't take medications that are suspended in gelatin (derived from hoofs), or from continuously impregnated mares (Premarin-a portmanteau word coming from 'pregnant' and 'mare'). Veganism has strong ethical underpinnings. Vegans see all living things as part of a balanced ecosystem, and make choices that benefit or at least do minimal harm to that connected system. If you'd like a more comprehensive and helpful guide to becoming vegan, check out Tully Zander's site: http://www.vegansfirst.com/
Fruitarian: Eats only fruit (which includes seeds). This is a real thing, or so I am told, I have never actually met one. Fruitarians can be further restricted by eating only fruit or seeds that 'fall' from a plant. But before you fall off your paleo horse from laughing consider this fun fact: Dental studies of early hominids have shown that our ancestors ate a primarily fruitarian diet, making it a more accurate definition of a paleo diet than the reducing diet of the same name that is in vogue these days.