The lights burned late in the seventh-floor campaign headquarters of Republican J. Marshall Coleman here last week as the gubernatorial candidate and his top aides hurriedly prepared a position paper on economic development.

The next morning, Coleman inveiled the statement at a press conference, upstaging by 72 hours a long-planned announcement on the same subject by his Democratic opponent for governor, Lt. Gov. Charles S. Robb.

Although the election is more than five months off, Coleman's backers said their candidate scored a coup with his statement. It was, they said, an illustration of how quickly Coleman is willing to move in the opening days of the race to take advantage of what many have described as a significant Robb weakness: his slow, sometimes ponderous style.

It also demonstrated that in a campaign in which the candidates' conservative philosophies often mirror each other, style rather than issues may provide the easiest way to distinguish between the two men.

"You [the news media] always refer to us as Tweedledum and Tweedledee," Robb said in an interview last week. "But I'm not going to change my positions to make a difference between us. So it is a matter of style."

The lack of contrast on economic issues became apparent after both plans were released. Even the language was similar. Coleman labeled economic development "the most important responsibility a governor has" and Robb called it "the single most important challenge that will face Virginia's government during the remainder of this century."

Despite the different amounts of time each man spent preparing his economic pronouncement and the length of the statements -- Coleman's was 16 doublespaced pages, Robb's was 50 pages singlespaced -- the differences that emerged were basically those of style.

Robb, who had worked for weeks on his position paper, appeared agitated that reporters wanted him to summarize the wordy document.

"It's not designed to provide bumperstrip language," he snapped. "You have to read the document to understand what I want to say."

Robb backers claim that another Coleman campaign approach to the state's economy -- working at a series of jobs around the state -- appears to be aimed at generating publicity.

While Robb was closeted with experts, preparing detaifled proposals for economic development, and soon-to-be released papers on energy, education, criminal justice and the elderly, Coleman was getting what his staff calls on-the-job training, attempting to learn first-hand how state government affects the lives of its citizens.

Since January, Coleman has put in a full day at each of 17 occupations, including hospital attendant, history teacher, park ranger, welfare worker, book store clerk, police radio dispatcher, road inspector, complaint taker for utilities and gas station attendant.

Their candidate, the Robb backers say, has been working four to six months behind the scenes weighing recommendations of a bipartisan task forces for his first position paper of the campaign.

Coleman's supporters counter that Robb's finished product, while similar in approach to Coleman's shorter exposition, was classic Robb -- thorough, thoughtful, and boring.

A careful reading of Robb's 100-point economic development proposal revealed some minor differences, including their assessments of how successful Virginia has been in keeping and attracting business and industry.

Under Republican governors, Robb said, Virginia's economy "is not as vigorous as it once was," adding that since 1974, the state's growth "did not conspiciously exceed the national average." It would, however, be "imprudent to dismiss the last six-year period of relatively unimpressive economic performance," he said.

Coleman, apparently anticipating that Robb would criticize the performance of GOP Gov. John N. Dalton, promised to continue "the leadership of a succession of able governors." He said the state needs no drastic economic redirection . . . no major economic overhaul."

Both men want to promote tourism, improve transportation, develop coal as a primary energy source, aid small farmers, deepen the harbor at Hampton Roads, reduce government regulation, retain the right-to-work law, decrease youth unemployment and expand foreign trade.

Robb campaign strategists believe the succession of position papers released by Coleman at weekly press conferences, and his working at different jobs, bolster their candidate's claim of being the serious candidate, compared to "the fluff candidacy" of his opponent.

Coleman's press secretary, David Blee, responded that Robb is "hoping to use accusations like 'fluffery' to distract from the fact that despite his 50-page statement, his conclusions are no different than Marshall's."

Anson Franklin, Coleman's campaign manager, is amused by suggestions that Coleman's economic development paper was slapped together to beat Robb to the punch.

Franklin confirmed that he, Blee and research director Rick Claybrook worked late that night with Coleman to complete the paper. But that was "just the usual fine tuning we do on all our statements," he said.

"If was our eighth position paper, and we announced the press conference three days in advance -- earlier than any of the others. At the time, Robb hadn't issued any, so I guess you could say we beat him with a lot of issues -- gun control, drunk driving, industrial development."

As to Robb's esire to be taken seriously by Virginia's voters, his press secretary, George Stoddart, said, "it's not difficult to portray Chuck as serious, because he is."