Gatsby and Tom? compare and contrast?

In the novel The Great Gatsby by F. Scott Fitzgerald, Tom and Gatsby are similar in many ways, for example their riches, but what other ways are they similar? A major difference between them is the way in which they use their wealth/ ranking in society (Tom = power and Gatsby=love for Daisy) but are there any other differences? Although Tom is portrayed in the novel in an extremely negative light, why does Daisy choose to remain with him instead of leaving him for Gatsby (security reasons?)?