With his bow tie, horn-rimmed glasses and baggy pants, Sen. Paul Simon of Illinois has more than enough to set him apart from the other Democratic presidential candidates. But the important differences are of substance, not style.

While his rivals try to avoid offending any groups that might block their nomination, Simon seems almost eager to step on the toes of interest groups that could make or break his candidacy. Call it refreshing or suicidal, American voters haven't seen such a campaign style in a long time.

Consider a few of the powerful egos Simon has bruised since he arrived in the Senate in 1985:Television executives. Simon's campaign to reduce television violence doesn't sit well in network board rooms, where a popular shoot-'em-up is revered as a financial lifesaver. A candidate does not lightly risk the hostility of those who control the most important campaign medium.

Civil libertarians. In a rare confrontation with the American Civil Liberties Union, which worries about government interference with television's content, Simon insists he doesn't want censorship. Calling himself a "lifelong civil libertarian," he said he can't accept the idea that a free society can't find a way to curb mayhem on the tube.

Tax reformers. Simon was one of three senators who voted against the tax-overhaul bill. He said the bill could do nothing to alleviate budget deficits. He also surprised fellow liberals by supporting a balanced-budget amendment.

The coal industry. Though he represents a coal-producing state, Simon has insisted that acid rain is an issue that must be dealt with.

The tobacco industry. Simon supports an increase in the excise tax on cigarettes.

Big oil. Simon has proposed that by 1992 at least half the gasoline sold in the United States contain 10 percent ethanol, a corn derivative. The Transportation Department is concerned about the plan, which would leave the ethanol portion of the gas free of federal excise tax. Simon says his plan would help the farmers, reduce U.S. dependence on imported petroleum and contribute to cleaner air.

Budget cutters. Simon backed an $8 billion plan that would guarantee public-service jobs to those unable to find work. He said his plan would eventually save money by breaking the welfare cycle.

Ollie North fans. Though his mail ran 50 to 1 in favor of Marine Lt. Col. Oliver L. North, Simon disdained "finger-in-the-wind politics" and said he doesn't consider someone who fails to uphold the law to be a hero. Simon has also opposed the jingoistic deemphasis on the teaching of foreign languages; on practical grounds, he notes, Americans must know how to communicate with potential customers in a global market.

Simon's independence is also reflected in his stubborn devotion to his trademark bow ties against the advice of many political supporters -- including the late Sen. Paul Douglas (D-Ill.), whom Simon admired deeply.

In fact, Simon says he believes his rumpled look is an advantage. "It's slick not to be slick," he told our reporter Gary Clouser. His wife, Jeanne, said his appearance makes him seem approachable -- like "everyone's favorite history teacher."