virginia voters will nominate a Democratic candidate for governor Tuesday, choosing between a crusader who has summoned the party to disown its conservative past and a methodical political practitioner who wants to accomodate that past in a moderate-conservation coalition.

On one side stands former Lt. Gov. Henry E. Howell Jr., 56, the often whimsical gadfly of the Virginia political conscience. He has built his political career on the issues of civil rights, consumer protection, tax reform and equal legislative apportionment. He has worm the names of his enemies, chief from the old political organization built by the late Gov. and Sen. Henry F. Byrd Sr., like badges of honor throughout his nearly 30 years in public life.

On the other side stands former Atrorney General Andrew P. Miller, 44, a man as controlled and cautious as Howell is flamboyant. He has sought to prove that it is possible to espouse some of the same progressive principles as Howell without alienating the conservative voters from which the Virginia Democratic Party once drew its strength. Afte seven years as attorney general, he displays a wide rangining knowledge of state government. His supporters stress his competence and his electability against conservative Republican opposition.

The contest between these two is the focal point of a statewide primary that also includes apparently close races for Democratic lieutenant governor and attorney general nominations. Republicans chose their ticket for candidates for statewide office at a convention in Roanoke last weekend.

Primary elections of party nominees to run for the House of Delegates next fall also will be held in many parts of the state, including every city and county in Northern Virginia.

Most of the contests involve Democrats, but Republicans are holding House primaries in Fairfax, Prince both major parties are choosing a nominee for sheriff in the primary in Alexandria.

Local government bond issue proposals will be on the ballots in scattered parts of the state, including Fairfax, Prince William and Loudoun counties. The willingness of voters to approve borrowing for parks, schools and other public facilities will be watched as a possible indication of how six proposed statewide bond issues totaling $125 million will fare next November.

The contrasting personalities and political styles of Howell and Miller have dominated the gubernatorial campaign, obscuring differences between the two over state government issues.

Among the differences are these:

TAXES - Howell has flatly promised there would be no increase in general taxes during his administration. Miller, calling howell's promise "irresponsible," has said that he expects that there will be no need for a tax increase. He says normal revenue growth, cobined with budgeting efficiencies he plans to introduce, will prevent the need for higher taxes.

UTILITIES - Howell advocates elimination of the fuel adjustment clause permits electric utilities automatically to pass on changes in fuel costs to customers.Miller favors retention of the clause. He says its elimination now might prevent customers of Virginia and Electric Power Co., the state's largest utility, from realizing savings that may result from increased reliance on nuclear fuel during the next year.

PUBLIC EMPLOYEE BARGAINING - Collective bargaining contracts with public employee unions are illegal in Virginia under existing law. Howell favors legislation that would permit but not require cities and counties to enter into collective bargaining agreements with their school teachers and other public employees. He has said he will set up collective bargaining procedures for executive department employees by executive order.

Miller flatly opposes public employee collective bargaining. He says it fosters hostile relationships between state and local governments and their employees. He also contends that the abscence of formal contracts and bargaining need not preclude "open communications" between governments and government workers. He often cites low state government salaries as a barrier to increased government efficiency and has promised to restructure salary scales. Howell also advocates boosting many state worker's salaries.

HOME RULE FOR CITIES AND COUNTIES - Howell says he favor loosening the tight rein kept on local governments by the General Assembly. He favors a constitutional amendment permitting cities and counties to take action not expressly prohibited by the legislature. Current law permits them to take only those actions expressly approved. Miller fovors study of local state relations by a state commission before altering the fundamental powers of local governments.

On issues of special interest to Northern Virginians, the two candidates are in general agreement. Both favor state aid to Metrorail construction, subject to a final decision on how big the system should be. Both have promised a regional state government office in Northern Virginia and appointment of a greater number of Northern Virginians to state policy-making positions.

The great differences of personality and political style that have separated Miller and Howell in this campaign also reflect the conflicting roles the two candidates have played in the recent, turbulent Democratic Party history in Virginina.

That tubulence has cost the Democrats their former supremacy in the state. Although the party, still has overwhelming majorities among local officeholders and legislators, republicans hold a majority of the state's congressional seats and Democratic candidates have lost nine of the last 12 statewide races (including presidential contest) in which the party ran a candidate. The only Democratic winners since 1968 have been Miller in two races for attorney general and the late Lt. Gov. J. Sargent Reynolds.

Throughout that period, Howell has been a symbol of the proposition that Virginia Democrats should break irrevocably with the conservative Byrd era. Miller, on the other hand, has become the leader of the movement to establish a broad party base of blacks, older conservatives and young suburban voters - many of whom are alienated by Howell's rhetoric and personal style.

"When the voters are counted June 14," Miller said last week at a news conference in Richmond, "we expect to show an across-the-board appeal to every group and section of the state. That's the kind of broad-based appeal my campaigns have always generated and that's the kind with which we expect to win this year."

Howell, on the other hand, has rejected Miller's appeal to the right. Last week he talked of the figures of the party's conservative past - people like former Gov. William M. Tuck whose segregationist, union-baiting stands are anathema to most hwo identify themselves as Democrats today. "There is a place for Bill Tuck," Howell said in Virginia Beach, "but not in the Democratic Party of today."

There has been much evidence that Miller has reclaimed in this campaign a large part of the conservative Virginia electorate, once Democratic that has drifted toward independent or even Republican identification in recent years.

Of these Miller supporters, Howell said in party-loyal Southwest Virginia recently, "These are the people that worked for Richard Nixon against John F. Kennedy . . . and Gerald Ford against Jimmy Carter."

President Carter's son Jack campaigned for Howell for three days in Virginia last week and at one point called MIller, "more of a Republican, philosophy-wise."

Howell clearly concedes to Miller the more conservative part of the electorate. He has concentrated on turning out a large number of Howell loyalists, including black Virginians and union members, who, he hopes, will continue to give him large majorities.

As a result, the election on Tuesday appears to come down to a test of Miller's ability to turn out a large vote on the right and to make inroads into Howell's black and labor constituency - voter blocs that Miller also has attracted in his past races against conservative Republicans.