In Type III D&D, the point-buy values are 8 for 0 points, 9 for 1 point, 10 for 2 points, 11 for 3 points, 12 for 4 points, 13 for 5 points, 14 for 6 points, 15 for 8 points, 16 for 10 points, 17 for 13 points, and 18 for 16 points. i.e. each ability score costs a number of points equal to the ability score modifier of the current ability score (min 1).
In Pathfinder, the point-buy values are 10 for 0 points, 11 for 1 point, 12 for 2 points, 13 for 3 points, 14 for 5 points, 15 for 7 points, 16 for 10 points, 17 for 13 points, and 18 for 17 points. i.e. each ability score costs a number of points equal to the ability score modifier of the next ability score (min 1).
Likewise, the number of ability score point buy points that you are allotted for various campaign flavors (low power vs. high power) is different between Type III D&D and Pathfinder.
The method by which you generate ability scores does not matter all that much, as long as the players either all agree to use the same method, or all agree to use different methods, knowing that the power levels of the characters will vary slightly with different ability scores (as well as a number of other factors).