Crows will glide rarely, but only ravens truely soar and circle. Overall, if you get a look at a perched bird, ravens are shaggier. The big clincher ('cept call) for me is the tail shape. Ravens have a distinctly wedge-shaped tail, and crows' are more fan-like. If you need help remembering, Raven=V, Crow=C, the letters in their names. Neat little memory device I learned from people met in my travels.