Resplendent in a white naval uniform, President Anwar Sadat today came for a peace celebration with a difference to this dusty capital of the Sinai, which was returned to Egypt yesterday after 12 years of Israeli occupation.

While the doves of peace and the cheering crowds had afamiliar ring, today in El Arish there was an unmistakable new air of accomplishment. The rewards of peace that Sadat long has promised the Egyptian people were no longer a hope for the future. They were real.

When Sadat emerged from the victoy Mosque after prayers of thanksgiving, butchers slit the throats of two water buffalo that lay trussed on the ground outside. As Sadat climbed into his open jeep station wagon to resume his joyous tour of the shabby, Windswept Town, young men dipped their hands in the blood of the ritual sacrifice.

Raising their dripping hands over their heads, they joined the waving, applauding throng that welcomed the Egyptian leader.

Sadat's visit to the dusty oasis town on the shores of the Mediterranean, returned to Egypt as the first tangible fruit of the peace treaty, was his first since 1952 when as a young Army officer he was called to Cairo by Gamal Abdel Nasser to take part in therevolution.

His return was every bit the theatrical success the Egypitans planned, and it had moments of genuine emotion. Tears glinted in Sadat's eyes when he hoisted a huge Egyptian flag over El Arish.

Sadat received an unrestrained welcome from the 30,000 inhabitants, who cheered and waved and shouted their support and pelted his motorcade with sweets, much as the residents of Cairo did when Sadat returned from his historic visit to Jerusalem in 1977.

The Egyptian leader made no official statement at the ceremony. He will host U.S. Secretary of State Cyrus Vance and Israeli Prime Minister Menachem Begin at a ceremony Sunday that will reenact Friday's brief official military turnover.

Sadat's official yacht is anchored about a mile off the splendid palm lined beach, but he arrived in a custom-fitted Hercules C130 transport plane. The Israeli Army still operates a communications post at the airport, and Israeli officers mingled casually with the Egyptians as they waited for Sadat.

As soon as he stepped from his plane, Sadat and his top advisers knelt on prayer mats spread upon the sand for players of thanksgiving led by the grand sheik of Cairo's Al Azhar Mosque, a little public relations touch that reemphasized to Sadat's Moslem and Arab critics that he has the support of the premier theological institution of Islam.

Sadat visited a long-neglected memorial to victims of the first Arab-Israeli war in 1948. Then he flew to a makeshift arena decorated with arabesque tenting where he and all his political and military associates kissed the enormous flag he was to run up the pole.

Doves were released, balloons went up, and the band played "Biladi, Biladi" (My Country, My Country), the new Egyptian national anthem that was adopted after the signature of the peace treaty.

There followed the kind of motorcade through the streets at which Sadat has become so adept over the years. He rode standing in his jeep, waving to the cheering crowds and smiling at the applause and greetings they showered down upon him from buildings festooned with banners supplied mostly by the government.

"Welcome Sadat, hero of war and peace," they said. "El Arish welcomes the hero of peace." And, more pointedly, "Today El Arish, tomorrow Jerusalem."

Above the banners flew two flags, those of Egypt and of Palestine, the latter a non-too-subtle reminder of Sadat's insistence that the treaty restoring the Sinai to Egypt is not the separate peace his Arab critics say it is.

One Palestinian flag flew over the mosque where he had his prayers. Another flew over a cafe near the abondoned railroad station that still sells Israeli beer and quotes the price in Israeli pounds. An attempt to pay for a round of beers in Egyptian money provoked a lively debate behind the counter, followed by big grins by welcome.

In fact, El Arish rapidly is becoming a fully Egyptian town once again. Taxi drivers have begun removing their Israeli tags and replacing them with hand-drawn Egyptian facsimiles. The Egyptians have established bus service, and an enterprising Cairo ice cream vendor is patrolling the streets in his truck. CAPTION: Picture, President Sadat, in navy admiral's uniform, kneels in prayer at El Arish airfield. AP%