Flanked by leaders of Nicaragua's new government, Cuban President Fidel Castro declared in a national day speech that despite similarities between their revolution and his, Nicaraguans would follow their own path.

Speaking Thursday, on the 26th anniversary of the attack that launched the Cuban revolution, Castro lavishly praised the Sandinista guerrillas and their political allies who overthrew Nicaraguan dictator Anastasio Somoza.

But he took some pains to state that predictions that Nicaragua would become "another Cuba" would not come true.

Castro also came close to praising the United States for staying out of the Nicaraguan civil war and even made a polite reference to the once-reviled Organization of American States.

By not intervening in Nicaragua, Castro said, the United States averted "a gigantic Vietnam...throughout Central America and in the rest of Latin America."

In a ceremony yesterday, Cuba formally reestablished diplomatic relations with Nicaragua broken in 1959.

Two members of Nicaragua's five-member governing junta - businessman Alfonso Robelo and leftist politician Moises Hassan - were on hand for Castro's speech in the city of Holguin. Castro said the visit was initiated by the Nicaraguans, who flew here in a Cuban plane that had delivered food, medicine and hospital tents to Nicaragua.

Castro said the visit of the two junta members and a number of other Nicaraguan guerrilla and political leaders was proof of their honesty.

"They do not go around denying they are friends of Cuba," he said. "They do not fear that the Nicaraguan revolution will be confused with the Cuban revolution. They are two profound revolutions and, in many ways the same and in many ways different."

"Each country has its path, its problems, its style, its methods and its objective. We have ours and they have theirs. We did it in a certain way...and they will do it their way."

Somoza and some U.S. government sources charged that Cuba supplied arms to the Sandinistas. The charges were not confirmed independently, but Castro did provide training and some financial support to the guerrillas.

In his speech, Castro warned against people who "want to establish similarities between what occurred in Cuba and what has occurred in Nicaragua." These people, he said, seek "pretexts to apply aggressive measures against the Nicaraguan people."

Recalling the U.S.-sponsored embargo against his government in the early 1960s, Castro said Nicaragua must be "alert" to the possibility of similar actions against its revolution.

But he added that times have changed and "imperialism has learned something - not much, but something."

In an unusually friendly reference to U.S. policy, Castro said, "The U.S. government has at least been wise once. It is much better...to send food instead of bombers and Marines as they did in Vietnam and in so many other places. "

Castro praised the Latin American nations that blocked a U.S. move to send an OAS peacekeeping force to Nicaragua.

He called the move, reportedly initiated by national security adviser Zbigniew Brzezinski, an effort to "prevent revolutionary peace...to seize triumph from the people."

In referring to the OAS vote to block the force, Castro mentioned the organization's name, in his words, "for the first time without epithets."

This apparent softening of Castro's attitude toward the inter-American organization came two weeks after the top-ranking Cuban diplomat in Washington, Ramon Sanchez Parodi attended an OAS meeting as an observer for the first time since Castro's government was suspended from the organization in 1964.

The White House announced yesterday that President Carter has ordered that emergency food and medical supplies by sent to Nicaragua. The announcement also said that Ambassador Lawrence A. Pezzullo, who left Managua following a dispute with the Somoza government, will return here today to present his credentials to the new government.

Meanwhile, Sen. Richard Stone (D-Fla.) characterized as a "whitewash" an assertion by Secretary of State Cyrus R. Vance that "there is no evidence of any substantial increase of the Soviet military presence in Cuba over the past several years or of the presence of a Soviet military base."

Vance's comments were in a letter responding to Stone's request for information about the possible introduction of Soviet combat troups into Cuba. Senior administration officials have said they have intelligence that a "command structure" for a Soviet combat brigade has been established on the island, but they also say there is no evidence that the troops to flesh out such a brigade are in Cuba.

At a press conference, Stone charged that Vance's reply was "dodging the issue" of whether the Soviets are engaged in activities that violate a 1962 agreement barring Soviet offensive forces in Cuba.

"If we don't object when a small base is established, we will lose our right to object when it ripens into a large base," he said. CAPTION: Picture, Sandinista soldier sleeps on a mattress dragged onto the porch of a house belonging to ousted president Somoza. UPI