George Bush expects to be elected president by riding on Ronald Reagan's coattails, but at the same time he wants to keep secret his advice to the president over the past seven years. If he had original ideas, he hasn't made them public. If he benignly went along with everything Reagan decided, then who will George Bush turn to if the Oval Office is his own?

What worries White House conservatives -- those who call themselves ''true Reaganites'' -- is that there are differences between Bush and Reagan that should not remain hidden until inauguration day.

Take a look at Bush's wobbly stance on the Iran-contra scandal. He postures as a key player in the Reagan administration, but he expects voters to believe nobody told him about the arms-for-hostages deal. He was at an Army-Navy football game when the crucial decisions were made, he said. Bush also claims to have expressed private reservations about the little he did know. But no one seems to remember his remonstrances.

Then there is the wimp issue. Bush, the World War II fighter pilot, is no personal wimp. But his political courage deserves examination. His face-off with CBS anchor Dan Rather was hailed as macho because he put Rather on the spot. That's the kind of machismo that goes on around the quiche plate. Rather isn't running for president.

In a similar display, Bush stood up to a 15-year-old high school sophomore. In a school forum in Cedar Rapids, Iowa, the girl asked Bush about his stance on abortion. When he saw that she was taking her cue from a Jack Kemp campaign brochure, Bush took the brochure, tore it in half with a flourish and pronounced it ''finis.''

Being maulish with a minor and yelling at an anchorman doesn't give us an idea of how Bush would stand up to Mikhail Gorbachev.

It is politically expedient for Bush to tie himself to the ever-popular Reagan, but he must now demur on some decidedly un-Reaganlike things he has said in the past.

In the 1980 primary campaign, he vehemently derided Reagan's ''voodoo economics,'' a charge he has not repeated since.

Respected journalist Elizabeth Drew says Bush told her he wasn't gung ho about Reagan's Strategic Defense Initiative and that he had told Gorbachev as much. She published the story in The New Yorker magazine, and Bush's spokesman denied the vice president had said that.

Our own investigation shows that even if Bush won't reveal his own colors, his top appointees will. A good case in point is the control of sensitive Western technology.

The Reagan administration has tried to stem the flow of technology to the Soviet Union. But Malcolm Baldrige, the late commerce secretary and a Bush confidant, believed that too much interference by the Pentagon hampered the international flow of high-tech trade, which the Commerce Department was supposed to promote.

In 1984 a Presidential Task Force on International Private Enterprises, headed by Dwayne Andreas, recommended that the Pentagon, the CIA and the National Security Council be left out when the Cabinet was considering trade matters. Andreas had the backing of Bush staffers. When the president learned what the task force was up to, he canceled a luncheon with Andreas. Instead, Andreas got five minutes of the president's time in a ''drop by.''

Bush's two top men in the administration, Treasury Secretary James Baker and Baker's assistant, Richard Darman, finally got the job done. They created an Economic Policy Council to deliberate trade matters and didn't invite the Pentagon to join.

That crucial change makes it possible, for example, for Commerce Secretary William Verity to deal on multibillion-dollar high-tech projects with the Soviets without asking the Pentagon how it would affect the balance of military power.

The example of high-tech trading suggests there may be other ways in which Bush differs from the man he wants us to think is his mentor, Ronald Reagan. As one high-level administration official told us, ''George owes it to the American voters to come out of the closet and explain his differences with the president. It's certainly one way he could put the wimp image permanently and substantively to rest.''