Crow account for an entire family of birds, Corvidae, that includes the raven species. That is, all ravens are crows, but crows can be ravens, jays, or magpies. In the United States, most people are referring to the American Crow when they use the term. While this blackbird and the raven have many similarities, there are differences in their appearance, behavior, and habitat.
When birdwatching, it's easy to recognize differences between a raven and a crow to help identify the bird spotted. The easiest thing to note is their size. A raven, such as the North American Corvus corax, is larger than an American Crow, Corvus brachyrhynchos. Ravens average 25 inches tall (64 cm) with a 4 foot (122 cm) wing span, about the size of a hawk, while crows are around 18 inches (46 cm) tall and their wings span 3 feet (91 cm), similar to a dove. The beak of a crow might look slightly thicker than that of a raven.