Another of the localized conflicts that make the Arab world so volatile and impede the unity that Arab leaders profess to seek was apparently defused this past week with an amicable meeting between the heads of state of North and South Yemen.

Official accounts of their talks said they agreed on "genuine and sound steps" toward unification.

Diplomatic specialists in Yemeni affairs said they doubt that this will actually result in a merger of the two states, which have wuite different economic and political orientations. Rather, they said, it indicates that the two may turn away from their former hostility to cooperation on matters of mutual interest.

For Marxist South Yemen, the talks mark another step out of its long diplomatic isolation, a process that began when it established diplomatic relations with Saudi Arabia a year ago and, in exchange for Saudi economic aid, cut off active military support for the Communist-dominated insurgency in neighboring Oman.

Before that, South Yemen -- the poorest Arab country -- was a parish on the Arabian peninsula, almost wholly dependent on the Soviet Union.

Improved relations between the two Yemens certainly have the support and probably the active encouragement of Saudi Arabia, which provides economic aid to both. The border between the Yemens meets the sea at the narrow Bab el Mandeb strait, the entrance to the Red Sea which is of vital strategic importance for Saudi Arabia and its allies, Egypt and Sudan.

The Saudis have been working actively for regional efforts at protecting the strait, which they see as possibly threatened by the chaos in Ethiopia and by potential struggles among the African states on the west side of the strait over the French Territory of the Afars and Issas, which is to become independent this summer.

Ibrahim Hamdi, president of the Yemen Arab Republic, or North Yemen, and Salem Rubaya Ali, head of state of the People's Democratic Republic of Yemen, or South Yemen, met at the border town of Qatabah. It was believed to be their first meeting on Yemeni soil since 1974, when Hamdi took power in North Yemen in a coup -- a move that effectively ended previous negotiations toward a merger.

Those talks began after a border war between the Yemens in 1972. Despite historic tribal and religious ties, the two countries were uneasy neighbors after South Yemen, the former British colony of Aden, gained independence in 1967.

An Arab League mediation mission helped end that war with a peace agreement in which the Yemens agreed to establish a single state with its capital at Sanaa, now the capital of North Yemen. That agreement went the way of so many similar accords among Arab neighbors, with no real merger ever actually effected. By the spring of 1975, after the pro-Saudi, pro-Western Hamdi had taken power in Sanaa, North Yemen was accusing South Yemen of "acts of sabotage" over the border.

Then came Saudi Arabia's opening toward South Yemen, and with it Saudi pressure for a lessening of tensions on the peninsula. In October, the two Yemeni heads of state held a fence-mending session at the summit conference in Cairo, where other Arab leaders are said to have suggested that they renew their cooperation.

The outcome of their meeting last week fits in with the pattern of events in the Arabian peninsula that has developed over the past three years -- a lowering of hostility and tension under the diplomatic patronage of Saudi Arabia, and a steady lessening of Soviet influence.

Particularly in North Yemen, which formerly was pro-Soviet and received substantial Soviet military assistance, the turn to the West under Hamdi has been dramatic. Last year he turned to the United States for arms, and he is currently courting France assiduously.

Foreign Minister Abdulla Asnaj was in France last week for talks covering, among other things, the proposed independence of the French colony across the Bab el Mandeb. French Foreign Minister Louis de Guiringaud is understood to have accepted an invitation to visit Sanaa.