Yes, Tom's money is old money, meaning that he inherited it rather than works for it. In chapter 1 when Nick first discusses his cousin, Daisy, and her husband, Tom, he describes Tom's family as "enormously wealthy," saying that when Tom had come East, "he'd brought down a string of polo ponies from Lake Forest. It was hard to realize that a man in [Nick's] own generation was wealthy enough to do that." This, in addition to the fact that Tom lives in the more fashionable East Egg (as opposed to West Egg, where Gatsby lives) allows us to understand his unique status in comparison to Gatsby. Later, when Tom grows suspicious of Gatsby, he says that "'A lot of these newly rich people are just big bootleggers, you know.'" It turns out that he is absolutely right. Gatsby has earned his fortune, albeit illegally, and both of these facts mean that his money is less valuable, in a way, than Tom's because it does not confer the same status.
Tom Buchanan may be a jerk, but he doesn't do anything illegal, as Gatsby does. However, he does cheat on Daisy, something Gatsby would never do, as Gatsby is utterly devoted to her. Early in the book, Tom takes Nick to meet his mistress, Myrtle, saying, "'I want you to meet my girl.'" The pair of men then meet Myrtle in the city so that Tom and Myrtle can sleep together while Nick waits a room away. Nick later calls him a "libertine," and Gatsby is certainly not that. Gatsby, on the other hand, tells Nick how -- even long ago -- "He felt married to [Daisy], that was all." Gatsby is devoted to Daisy in a way that Tom never has been.
There are quite a few differences between these two men. First of all, although both men are extremely wealthy, Tom's money came from his family wealth while Jay Gatsby made his money on his own, though he did it illegally. Tom also is characterized as a violent and prejudiced person who does not see why anything should be any way but his own. He looks down on people because of who they are or where they are from. Meanwhile, Gatsby's contrast is shown in how gentle he is toward Nick, Jordan, and especially Daisy, and in the fact that he is business partners with a Jewish man -- Meyer Wolfsheim. Finally, whereas Tom seems to be the one who is evil, it is actually Gatsby who is corrupt in business and who expects Daisy to leave her husband and child to be with him.