The difference between a raven and a crow can only be determined by a close examination. In crows, the base of the feathers is pure white, with a line of marked division. With ravens, there is a gradual change from black to smokey grey. They are often mistaken for currawongs. Ravens have blue eyes, whereas the currawongs are yellow.
They are usually alone or in groups. The collective noun for ravens is 'unkindness'. My observations of ravens, are that when in a flock, they land in trees, fly off and around and return to the tree. Fascinating to watch.
Their feeding habits almost rival seagulls – eat anything. They are often sighted rummaging through rubbish bins looking for food. One photo I like is of a raven that looks like it had scored a chicken nugget.
Historically, the ravens of the Tower of London are a group of nine captive ravens resident at the Tower of London. Their presence is traditionally believed to protect the Crown and the Tower; a superstition holds that "if the Tower of London ravens are lost or fly away, the Crown will fall and Britain with it." Totally untrue of course, but a quaint tradition.
Magpies are indeed a nice bird. We used to have one that lived in a tall tree opposite and almost every morning as I walked into our lounge room it saw me and made a graceful glide onto our balcony rail. Unfortunately the tree was cut down.