The suitcase bomb that killed seven people waiting to board a Turkish airlines jet at Orly Airport in Paris on July 15 has set western intelligence and counterterrorist experts to searching their files for information about the Armenian group that claimed responsibility for the lethal blast.

The attack, one of the bloodiest in the Armenians' unremitting struggle against Turkey, does not necessarily herald an escalation of the violence, the experts say, but they express concern about the lack of basic information on the resources and capabilities of the two main groups concerned.

They are also worried about what appears to be a qualitative change in the character of Armenian terrorist activities: an increasing readiness to attack targets indiscriminately.

Although relative novices in the murky world of international terrorism, the Armenians have an impressive track record of political violence.

In the last decade they have killed more than 30 people around the world, mostly Turkish diplomats, according to the Turkish government. The day before last week's Orly bombing, another Turkish official was shot to death at point-blank range outside his home in Brussels.

The geographical scope of the attacks is also striking.

Eastern and western Europe, Canada and Australia have all suffered Armenian violence. In 1982, according to FBI figures, there were five officially defined Armenian "terrorist" incidents in the United States: two attempted bombings, one bombing and two assassinations.

The Armenians say that they are seeking vengeance for the massacre of 1.5 million of their people by the Ottoman Turks between 1896 and 1915, but successive Turkish governments have refused to acknowledge responsibility for the killings or the numbers cited by the Armenians.

The best known and largest of the two known groups is the Armenian Secret Army for the Liberation of Armenia (ASALA). Its ideology is Marxist and thus theoretically internationalist, but it appears to have no real interest beyond attacking the Turks.

"Their grasp of political theory is about fourth-grade level, but they're certainly very dedicated," said one U.S. official. "One could say that these groups are the deadliest around, and if they're not the deadliest they're certainly amongst them."

Howard Bane, until 1980 the CIA's director of counterterrorism, described ASALA as "probably the most impressive in terms of effectiveness" of all international terrorist groups.

"They're brutal," he said. "They don't take hostages to negotiate. It's just out-and-out murder."

Founded in Beirut in 1975, ASALA lined up with the Palestinians and the Muslim Lebanese in their bitter civil war with the country's Christians. They forged close ties with radical Palestinian groups like George Habash's Popular Front for the Liberation of Palestine.

Last summer, when Israel invaded Lebanon and drove the Palestinians and their allies out of Beirut, ASALA lost its base.

Since then, experts say, the group may have relocated in Damascus. One indication of this is that several recently captured members of the group are Syrians of Armenian origin. Varadjian Garbidjian, who claimed responsibility for the Orly bombing, is Syrian-born, as is an ASALA member on trial in London on a charge of conspiring to murder the Turkish ambassador to Britain. But some recent communiques have come from Athens.

ASALA does not hesitate to kill non-Turkish bystanders who are near its Turkish targets, and favors bombings over shootings, according to the experts. Its technique is often amateurish and its members easily caught, they say.

But the counterterrorist experts speak with respect of the second known group, the Justice Commandos for the Armenian Genocide (JCAG).

"The JCAG are just incredibly good at it in terms of sheer deadliness," one said.

This smaller group, according to another expert, enjoys far wider support among Armenian communities abroad than does ASALA, as evidenced by generous collections raised for the defense of accused JCAG members. ASALA's leftist ideology and indiscriminate violence, as well as occasional attempts at extorting money, on the other hand, are repugnant to old established communal organizations.

JCAG's politics are rightist and nationalist, and in Lebanon it allied itself with the Christian Phalangists. It is concerned more with settling old scores than carving a utopian future Armenia out of eastern Turkey and the Soviet Republic of Armenia.

A typical JCAG operation, according to western and Turkish sources, involves the shooting, usually at point-blank range with a 9 mm pistol, of a low-ranking Turkish diplomat who cannot be assigned the kind of protection automatically given to ambassadors and other senior officials.

Both organizations enjoy the advantage of being based on a close-knit ethnic group not easily penetrated by intelligence services. Both are considered adept at creating one-time cells that disband after each operation.

Last summer's dispersion from Beirut seems to have affected the Armenians at it did the Palestine Liberation Organization: factional fighting has come to the fore, not only between ASALA and the Justice Commandos, but within them.

"What we see now," said Brian Jenkins, a leading terrorism expert at the Rand Corp. in Santa Monica, "is a resumption of the frequency of operations that we had prior to the invasion of Lebanon, not an escalation."

There is, nevertheless, concern about what appears to be a dangerous change in the style of ASALA operations. On June 16, the group launched an indiscriminate machine-gun and grenade attack in the middle of the grand bazaar in Istanbul.