Although I do not know the answer to the Mad Hatter's riddle posed to Alice in Lewis Carroll's Alice in Wonderland: "Why is a Raven like a writing desk?", I do know how to tell a raven from a crow!
I have heard raven and crow used interchangeably to describe any large black bird. In fact there are many ways a common crow and a raven are alike. They both are the same color, that is all black from beak to legs. They both exhibit boisterous, aggressive behavior if they feel threatened. It is not uncommon for either of them to drive off an owl or hawk. Both are highly intelligent, playful, and good at solving puzzles. (I personally witnessed a crow open my suet basket with ease and fly off with its prize!) So thievery is on their agenda as well.
Treasure stashing is a trait both share along with an obsessive attraction to shiny objects, like tinfoil and bits of broken jewelry. Food preferences include everything from road kill to fruits and berries, insects, snakes, birds and small amphibians. Both are known for their cast iron stomachs!
Both crows and ravens like to use tools and play games. They will often try to steal sticks and stones from one another. A fish crow will fly high with a shellfish and drop it on the rocks below to crack its shell.
Nesting season is the same for both of them, from March to June. Each uses the same kinds of nesting materials. Twigs and sticks are stacked loosely in a bowl shape for the foundation in the very highest tree top or on a ledge. Then the nest is lined with grass or lichens and animal fur to cushion the 4 to 7 blue-green with brown splotched eggs that will be laid.
Ravens and crows will raid the nests of other birds and eat the eggs and the nestlings, if they get a chance. Even though they are no match for the much larger birds, songbirds will mount a defense by joining together and diving at the black intruders. So it is a good idea to protect your backyard wild birds by providing nesting boxes and bird houses.
These amazing birds are also accomplished mimics. They both can imitate most any sounds they hear, including those made by humans as well as other birds.
SO HOW DO YOU TELL THEM APART? There are several ways. The flight pattern is different, for one thing. You've heard the phrase straight as the crow flies? Well that definitely applies to crows. But ravens like to soar and fly in meandering circles, like hawks. They are very acrobatic, and often tumble while in flight, just for fun!
Another difference: ravens are the equivalent of crows on steroids! Ravens measure 21 to 27 inches from beak to tail. Whereas a crow is only 17 to 21 inches in size. A raven's neck and upper body is thicker and beefier than a crow. And the throat feathers of a raven look shaggy because of the long feather shanks in the neck area. The beak of a raven is heavier and larger, too. A crow's tail has a fan shape that is particularly evident in flight. A raven's tail has more of a wedge shape, and is more squarish.