The tracks are somewhat different in that different subjects are taught in different years. The British track tends to cover things earlier, so moving from the British track to the American can be easier than vice versa. A previous poster was correct in pointing out that the American School in Doha (ASD) is the most expensive private school here. It does, however, have a pretty good reputation. Right next door to the ASD is Doha College, which is probably the best of the British track schools.