President Reagan used his hotel suite here as he does the Oval Office in the White House, receiving a stream of visitors for short meetings that Secretary of State Alexander M. Haig Jr. said today accomplished "in two days what might take literally months of diplomacy."

The bilateral meetings here gave Reagan an opportunity to establish a personal relationship, however fleeting, with leaders of 14 other nations, all but two from the developing world, and gave Reagan's spokesmen the chance to portray these exchanges as fruitful and marked by broad agreement.

His guests did not always agree with the U.S. characterization, however.

Haig told a crowd of reporters, for example, that Reagan and Nigerian President Shehu Shagari had discussed Namibia, Angola and other subjects and found "a remarkable convergence of views."

Haig's Nigerian counterpart, Foreign Minister Ishaya Audu, responded by calling Haig's description "a bit exaggerated."

"There are certainly a number of disagreements," the Nigerian said. On Namibia, the United States believes South Africa should be offered a carrot, while Nigeria thinks South Africa needs a stick to be made to relinquish the territory it rules in defiance of the United Nations, he said.

Audu said that the two presidents also disagreed on Angola, where the United States opposes the presence of Cuban troops. Nigeria considers the Cubans a matter for the Angolans to decide for themselves.

The pattern of divergent accounts was repeated after other bilateral meetings, including those with Chinese Premier Zhao Ziyang and with Venezuelan President Luis Herrera Campins.

However, Reagan won his major gamble in coming to Cancun by emerging without any scars. On the president's first venture into an arena dominated by the concerns of poor nations, Reagan found much more spirit of cooperation than of controversy.

The bilateral meetings also enabled Reagan and his aides to take a series of readings on the mood of this summit outside the conference hall. Even before Thursday's formal opening of the summit, Haig said, the U.S. delegation was "increasingly comfortable" here.

Several of the 30-minute hotel suite get-togethers here represented the president's first personal encounter with leaders of major nations.

For example, China and the United States both looked on the encounter between Reagan and Zhao as an important opportunity to gauge what directions U.S.-China relations can take during the Reagan administration.

And both sides reported that Reagan's meeting with Indian Prime Minister Indira Gandhi went very well. India was both pleased and embarrassed that Reagan singled out Indian agriculture for praise during one of the summit plenary sessions--pleased at the notice given to India's technological advances, but embarrassed because Reagan hailed the "green revolution" as a private sector accomplishment whereas India has a mixed private-state economy.

Reagan said that what he learned here did not change his thinking. He has said the United States will not increase levels of foreign aid, but thinks that developing nations best can make progress through the "magic of the marketplace."

Reagan muted that belief somewhat in his remarks here.

"You see, it is the strong who advocate free markets," Audu of Nigeria said. "Free markets are all right for the strong, but for the weak it's a different story."