First, the similarities. Well, obviously they're both "cows". They have the same body type, meaning they have the same type of stomach and digestive system. As silly as it sounds, most animals actually do have different stomach systems, this is geared towards their diets. So, when you hear "cows eat lots of corn" well, it is because they have a stomach system geared towards breaking down a lot of starch.
Cows actually have 4 chambers to their stomach (in order): rumen, reticulum, omasum, and abomasum. The rumen compartment is a giant fermentation vat, essentially, that breaks down food and transforms something humans can't eat (grass) into a nutritious, delicious product we can eat: beef! I hope you feel a little smarter - definitely a healthy dose of science today!
So, now the differences. As nicely and simply as I can put it: a beef cow is a cow that produces calves that will go into food consumption. The beef cow herself will produce one baby every year. She will live in a pasture and simply be responsible for taking care of her body condition and feeding a growing calf for 6 months. Those calves, mainly the males, will be fed a special, nutritious diet geared for them to grow and produce beef after they are weaned from their mothers.
Beef cows, naturally, have more "beef". They are a stouter kind of cattle that have more muscling. Some popular beef breeds are:
Dairy cows are totally different. Dairy cows produce calves every year, but they don't have the mothering instinct that beef cows do. Dairy cows will typically have a baby then enter the milk production cycle. Naturally they produce a lot of milk and they like to spend their time lounging around and giving milk - dairy cows like a routine! Dairy cows produce milk that will make "dairy" products like milk, cheese, sour cream, and ice cream.
A few popular dairy breeds include:
Here's a couple more pictures...can you tell if it is a dairy cow or beef cow? Have a great weekend!