The election in Prince George's County has produced a change in the political and social fabric of the suburban Maryland county much greater than the transfer of only one pivotal office, that of county executive, from Democratic to Republican control.

By roundly rejecting County Executive Winfield Kelly, returning Lawrence J. Hogan and Sue V. Mills to positions of power and overwhelmingly approving a Proposition 13-style measure to freeze the property tax levy, the voters seemed to be seeking a return to the days when life is Prince George's was simpler.

Kelly, who happened to be in control when the county was undergoing swift and profound changes - in racial composition, urban development and its form of government - was the logical victim. Hogan and Mills, the most identifiable opponents of one of those changes, court-ordered school busing, were the logical beneficiaries.

"Larry and I were the first two politicians in the county to take a stand against busing, and there was a definite spinoff from that in this election," said Mills, the former school board member who was elected Tuesday as a Democratic member of the County CounciL. "The spinoff was that when you take a stand against busing, it marks you as one of the people, not part of a system. That was what this election was all about."

Hogan, the Republican county executive-elect, spoke less stridently than Mills about busing this year, but there was little doubt that the voters remembered his earlier stand. His campaign organization included hundreds of conservative Democrats - blue-collar workers and their families, for the most part - who thought of Kelly when they thought of busing and how it changed their lives.

"It wasn't a racist chord that Hogan and Mills struck this year," said one Democrat close to Kelly. "I would call a kind of deep-rooted uneasiness with change, modernization, cool professionalism. Hogan and Mills represented something that many people could understand in a time when very little is understandable."

Kelly understood from the beginning of his 1978 campaign that he would be the target of this confusion and disllusionment. He tried, desperately at times, to convince his 730,000 constituents that Prince George's eventually would be a better place for all the changes. He even deliberately offered his name and his theme - "New Quality" - as the symbols of the county's transformation.

It was perhaps inevitable, then, that when the voters rejected this, when they decided that Kelly's attempts to alter the perceptions of the county were superficial, or distasteful, they took it out on him alone, and not on the Democratic Party, which controlled every elected office in the county.

"I often worried that Winnie tried too hard to create images and perceptions," said attorney William Meyers, one of his closest friends and advisers. "I worried that he made it even easier than ususal for people to identify everything good and bad with him. I told hme that every time a guy hit a pothole, or one of his kids flunked a class, he would say: "That damn little Winnie Kelly.'"

Kelly's Deomcratic colleagues discovered this to be true when they went out door-knocking during the campaign. Even during the primary, when Kelly had minimal opposition, the Democratic candidates for County Council and Maryland General Assembly seats were reporting back with countless stories about how all the voters wanted to talk about was Kelly, and most of what they had to say about him was negative.

"It was pretty obvious early on that the voters were not interested in rejecting the Democrats," said Del. Gerard Devlin of Bowie. "But you could see they wanted to protest the way things were by voting against Kelly and fo the property tax freeze."

For Devlin and the other Democratic politicians in the county, the question now is not why Kelly lost but what happens to their party without him. Kelly was one of the three top party leaders in the 1970s, and the other two - Maryland Senate President Steny H. Hoyer and political strategist Peter O'Malley - had already taken themselves out of the picture this year.

O'Malley, the person most responsible for forming and holding together the coalition of county Democrats that was often called a machine, withdrew from an active role on his own volition; Hoyer went out when he lost as Acting Gov. Blair Lee III's running mate.

"The era is over," said Thomas Mooney, a Democrat from Takoma Park who was elected to the House of Delegates this week. "I don't see anyone out there controlling things the way O'Malley, Hoyer and Kelly did."

Francis B. Francois, the veteran councilman who garnered more votes than any other council candidate in the county, said that the actually ended several months ago, when Lee and Hoyer were defeated in the Democratic gubernatorial primary.

"The whole structure changed permanently when that happened," Francois said. "The whole basis for what had occurred in the past eight years was gone. When Harry Hughes was elected and the Mandel-Lee regime ended, the Prince George's Democrats could no longer count on the sort of relationship where they would get whatever they wanted.

"The Breakfast Club (a bimonthly gathering of Democratic officials at which patronage appointments were decided) became irrelevant."

Indeed, there were signs of disarray in the once tightly controlled Democratic organization long before Kelly lost. A large number of Genral Assembly candidates ran solitary campaigns during the election, passing out their own literature and urging their supporters to vote only for them, something the O'Malley never tolerated when he controlled things.

Now, with kelly gone, a number of Democrats are picking over the leadership bones. Seven of the 11 Democratic councilmen are lobbying for the chairmanship. Democratic Central Committee Chairman Lance Billingsley is saying that he is best suited to direct the party affairs, something he did not do when Kelly and Hoyer and O'Malley were around. Francois, after his convincing reelection, appears ready to reassume a leadership role that he held in the early 1970s.

One of the few Democrats expressing little interest in filling the leadership vacuum is the woman who is unquestionably the most popular politician in the county - U.S. Rep. Gladys Noon Spellman. "I certainly would not move in," she said. "I could have done that years ago, but one of our weaknesses has been allowing one or two persons to make all the decisions."