American troops who have served in Iraq are finding that the tactical situation is quite different in Afghanistan. First of all, there are the mountains and hills. Iraq is mostly flat, at least in those areas where U.S. troops saw the most combat. Not only is Afghanistan hilly, but most of the "roads" are dirt tracks that the heavily armored hummers and MRAPs U.S. troops use have a hard time navigating. Without the ton or more of added armor, American hummer vehicles can speed across bad roads, or open terrain. But the weight of armor makes the hummer more difficult to maneuver cross country, or on bad roads, and requires driving at slower speeds to avoid damage to the suspension or other mechanical components. The Taliban prefer unarmored pick-up trucks or SUVs, which can quickly get away from the lumbering American vehicles.
If the Taliban take off on foot, they are also faster and more agile, because they are not carrying 30 or more pounds of body armor (vest and helmet). If the chase is close, the Taliban will drop most of what they are carrying (except their weapon) in order to get away.
The Afghans also fight differently than the Iraqis. For one thing, the Afghans are not as suicidal, and plan more carefully. The Iraqis favored the ambush, using fewer than a dozen people and a roadside bomb. The Iraqis were also enthusiastic about suicide bombers and using civilians as human shields. The Afghans prefer large scale attacks, carefully planned, and away from civilians. The Afghans also fight smarter than the Iraqis, although not a lot smarter. The Afghans are good tribal warriors, and those with some experience will pass it on to their buddies. But against Western troops, man-for-man, the Afghans are outclassed. But the Afghans will not shoot and run, like the Iraqis. The Afghans will shoot it out for hours, trying to drag out the battle until nightfall (when they have a better chance of sneaking away, in spate of U.S. night vision equipment.)
The Afghans are clever in that they will observe an American unit for days, weeks, or months, trying to find a weakness they can exploit. You cannot afford to get sloppy around the Afghans, because if they catch that lapse, they will exploit your mistake.
Local politics is also different in Afghanistan. In Iraq, there were small towns and villages that were the center of the political and social life for the surrounding rural area. Not so much of that in Afghanistan, where life was centered on which clan inhabited a valley, or part of one. Villages are fewer, with the most common feature being several buildings surrounded by a wall (which some of the buildings are part of.) In other words, the local architecture indicates a violent society, where your home is literally your castle (as much as one can call a mud brick fortress a castle).
The political situation is different in other ways. For one thing, the Afghan government is more in control of things than its Iraqi counterpart. Thus U.S. troops, in most cases, are not allowed to conduct building searches, Afghan police or troops must do this. The tribes have more political power, and many of the Taliban have kin in the government. Things can get more complicated, especially given the drug trade. Over 80 percent of the worlds heroin comes from Afghanistan, and the drug gangs have corrupted tribal leaders, as well as local and national government officials. The troops have to deal with this.