WASHINGTON » As it devises a new Afghanistan policy, the Obama administration confronts a complex geopolitical puzzle: two embattled governments, in Afghanistan and Pakistan; numerous militias aligned with overlapping Islamist factions; and hidden in the factions' midst, the foe that brought the United States to the region eight years ago, al-Qaida.

But at the core of the tangle are the two Taliban movements, Afghan and Pakistani. They share an ideology and a dominant Pashtun ethnicity, but they have such different histories, structures and goals that the common name may be more misleading than illuminating, some regional specialists say.

“;The fact that they have the same name causes all kinds of confusion,”; said Gilles Dorronsoro, a French scholar of South Asia currently at the Carnegie Endowment for International Peace in Washington.

This week, Dorronsoro said, as the Pakistani army began a major offensive against the Pakistani Taliban, many Americans thought incorrectly that the assault was against the Afghan Taliban, the force that is causing Washington to consider sending more troops to Afghanistan.

At stake is not just semantics. Grasping the differences between the two Taliban forces, and their shifting relationships with al-Qaida, is crucial to understanding the debate under way in the White House situation room. Though both groups threaten American interests, the Afghan Taliban—the word Taliban means “;religious students”;—are the primary enemy, mounting attacks daily against the 68,000 American troops in Afghanistan. Washington's biggest fear is that if the Afghan Taliban overrun the country, they could invite al-Qaida's leaders back from their Pakistani hide-out.

Alex Strick van Linschoten, a Dutch researcher who lives in Kandahar, in the heart of the Afghan Taliban's power base, said that while leaders of the two Taliban groups might say that they share common interests, the two movements are quite separate.

“;To be honest, the Taliban commanders and groups on the ground in Afghanistan couldn't care less what's happening to their Pakistani brothers across the border,”; said Strick van Linschoten, who has interviewed many current and former members of the Afghan Taliban.

In fact, the recent attacks of the Pakistani Taliban against Pakistan's government, military and police, in anticipation of the army's current campaign into the Pakistani Taliban's base in South Waziristan, may have strained relations with the Afghan Taliban, said Richard Barrett, a former British intelligence officer who tracks al-Qaida and the Taliban for the United Nations.

The Afghan Taliban have always had a close relationship with Pakistani intelligence agencies, Barrett said recently. “;They don't like the way that the Pakistan Taliban has been fighting the Pakistan government and causing a whole load of problems there,”; he said.

The Afghan Taliban, whose group is by far the older of the two forces, have been led by Mullah Muhammad Omar since he founded the movement in 1994. They seek to regain the power they held over most of Afghanistan before being ousted by the American invasion of 2001.

In an interview this week, speaking on the condition of anonymity, an Afghan Taliban commander expressed sympathy for the Pakistani Taliban, but said, “;There will not be any support from us.”; He said the Afghan Taliban “;don't have any interest in fighting against other countries.”;

“;Our aim was, and is, to get the occupation forces out and not to get into a fight with a Muslim army,”; the commander added.

Before 9/11, the Afghan Taliban hosted Osama bin Laden and the other leaders of al-Qaida, but the groups are now separated geographically, their leaders under pressure from intensive manhunts. On jihadist Web sites, analysts have detected recent tensions between al-Qaida, whose proclaimed goals are global, and the Afghan Taliban, which have recently claimed that their interests lie solely in Afghanistan.

Dorronsoro, the French scholar, said the Afghan Taliban were a “;genuine national movement”; incorporating not only a broad network of fighters, but also a shadow government-in-waiting in many provinces.

By comparison, he said, the Pakistani Taliban were a far looser coalition, united mainly by their enmity toward the Pakistani government. They emerged formally only in 2007 as a separate force led by Baitullah Mehsud under the name Tehrik-i-Taliban Pakistan, or Students' Movement of Pakistan.

After Mehsud was killed by an American missile in August, a fellow tribesman, Hakimullah Mehsud, took over after a period of jockeying for power in Pakistan's tribal areas.

Another complication for regional terminology: Most leaders of the Afghan Taliban are based in Pakistan, directing their forces from hide-outs across the border. Omar and his top deputies are believed to be in or around the southern Pakistani city of Quetta. Two other major factions in the Afghan insurgency are led by veteran Afghan warlords, Jalaluddin Haqqani and Gulbuddin Hekmatyar, who are in Pakistan's tribal areas, where the Pakistan Taliban is strongest.

Al-Qaida's leaders, including bin Laden, are believed to be hiding in the same tribal areas of Pakistan. While it has been weakened by American missile strikes, the terrorist network nonetheless is believed to have provided support for the Pakistani Taliban's strikes against the Pakistani government.

For the United States, regional experts say, the long-term challenge is to devise policies that peel away as many militants as possible from both Taliban forces, isolating al-Qaida and other hard-liners and strengthening the Pakistani and Afghan governments. But for a non-Muslim superpower, widely resented in the region, that is a tall order.

“;At the moment the ground isn't very well prepared for splitting the militant groups,”; said Stephen Biddle, senior fellow at the Council on Foreign Relations, who spent a month last summer in Afghanistan. “;The security trends are running in their favor.”;

Of course, if the United States' enemies in the region are complicated, so are its allies. In Afghanistan, President Hamid Karzai is seen as unwilling to take on corruption and tainted by fraud in the recent election, though he has now agreed to a runoff.

In Pakistan, with 172 million people, a population at least five times as large as that of Afghanistan, power is divided among the army, the intelligence service and two rival political parties—“;four actors,”; Biddle said, “;each of which sees the threat from the others as bigger than the threat from the militants.”;

Polls show that Americans, frustrated by the United States' supposed allies and confused by the conflict, are losing their fervor for the fight. “;The complexity of all this is hard enough for experts to understand,”; said Paul R. Pillar, a former CIA analyst now at Georgetown University. “;It's not surprising if it baffles a lot of ordinary people.”;