Tom is boyish and fully dedicated to acting out his fantasies. He is almost a Don Quixote style character, though he ultimately proves to be more in touch with reality and a more shrewd arbiter of truth than Quixote. 

Tom Sawyer is not as practical as Huck and this may stem from two things. First, Tom has a powerful imagination. Second, Tom is quite secure in his social position and stands to lose nothing if he charades should fail. 

Tom Sawyer changes very little between The Adventures of Tom Sawyer and the sequel, The Adventures of Huckleberry Finn.  One way to think about how the characters are different is to look at how the two books differ.  

Clearly Huck’s book is the more serious of the two.  Tom’s book is about adventures and misadventures, getting into trouble and avoiding punishment, and having fun.  These are Tom’s traits: playful, self-centered, and pushy.