he British-sponsored conference on Rhodesia ran into its first hitch today over the agenda, immediately stirring fears that the negotiations would run into the same difficulties that have plagued past efforts to settle the intractable independence issue.

The procedural differences between Britain and the Patriotic Front guerrillas over what to discuss first came as the Front and the Zimbabwe-Rhodesian government laid out diametrically opposed maximum negotiating positions on the second day of the conference.

None of the difficulties or differences were surprising as British Foreign Secretary Lord Carrington sought to steer the two warring parties to try to solve the 14-year-old problem.

Carrington, who called for a spirit of compromise in his opening remarks yesterday, said, "No one could have any illusions about the difficulties which will face the conference." He noted, however, that both sides had indicated a willingness to negotiate, adding "it is up to us to find a way forward."

British sources said there was no dismay in the British delegation over the developments, saying it would take time to see how serious the sides are about negotiating.

The procedural differences involve Carrington's plan to concentrate first on getting agreement on an independence constitution and then move to the difficult problems of disposition of the warring military forces and other transitional arrangements leading to an election.

Patriotic Front co-leader Joshua Nkomo disputed Carrington's claim that this was a constitutional conference, instead maintaining that it was a peace conference and that all the problems must be open for discussion.

The matter was pushed over until Wednesday when Carrington said he would respond to the stands laid out today by Nkomo and Zimbabwe-Rhodesian Prime Minister Abel Muzorewa.

It was evident from their remarks that both sides were engaged in opening round positioning. Muzorewa said he was here to achieve the lifting of economic sanctions and International recognition for his embattled government, while Nkomo said he and co-leader Robert Mugabe thought the conference had to deal with the problems caused by the war.

Muzorewa emphasized several times that he felt his black-led government, which took office as a result of controversial elections in April, had satisfied all the demands Britain had imposed for a settlement of the crisis that resulted from the white-minority's illegal declaration of independence in 1965.

In his 15-minute speech, Muzorewa made a strong plea that his government not be pressured into changing its constitution, which provides for considerable elements of white control and has been a key issue in the lack of recognition.

British Prime Minister Margaret Thatcher termed the constitution "defective" and called for changes at last month's Commonwealth summit in Zambia, which led to this week's conference.

He also accused Thatcher of not following through on what he called her commitment to move toward recognition, saying "nothing should now stand in the way" of his government being granted "rightful recognition."

Patriotic Front spokesman Willie Musarurawa called Muzorewa's speech "wishful thinking" and "simplistic," since he thinks the only problems are sanctions and recognition.

Zimbabwe-Rhodesian Foreign Minister David Mukome said in an interview tonight that his government would not tolerate any change in conference procedure, adding that "two weeks is the maximum we can allow ourselves to be outside our country" for the conference. Britain has set no time limit.

In his 23-minute speech, Nkomo criticized Britain's constitutional proposals saying they were "too vague" and called on the British "to take us into their confidence and show us what their real proposals are." He said some of the proposals are "seriously retrogressive" but gave no details.

Nkomo said an independent government "must be free to re-order the social, political and economic institutions . . . without having to pander to any racial, ethnic, tribal, religious, social or other interests," a reference to white authority entrenched in the Muzorewa constitution.

The wrangles, however, did remind many observers of the 1976 Geneva conference, the only other occasion where all the warring parties have gotten together. That meetings bogged down from the start in various procedures problems and broke down after two months.