What are the similarities between the characters of Macbeth and Magwitch besides the fact that they both experience a type of change?
Magwitch and Macbeth are both highly motivated by revenge, and both face betrayal by those close to them.
Although Macbeth is a noble and Magwitch is a common criminal, both of them are moved by a base desire for revenge. Magwitch felt betrayed by his partner Compeyson, who was able to convince the courts that he was a gentleman and Magwitch was a commoner. Magwitch was sent away to Australia, and he used his time there to save money to send to Pip to turn him into a gentleman to show the world that a gentleman can be made out of anyone.
Although Macbeth betrayed King Duncan in his quest for power, he felt betrayed by Banquo when he threatened to make it known that Macbeth killed Duncan. Macbeth kills Banquo both to protect himself and in response to this perceived betrayal.
In each case, the revenge results in disaster. Magwitch is killed trying to flee England, and Macbeth is killed by Macduff in his attempt to preserve himself as king in battle.
They are both percieved as people they are not, so Magwitch is seen as the 'Devil' as a child, although he is only doing what has to be done to survive (brings in social/historical context). Macbeth is seen as a loyal and nobleman but kills the king out of selfishness.