THe angle has nothing to do with it. The real determining factor is the distance between the pivot and the effective cable anchor point. A larger distance means the cable will travel more for a given amount of lever pull; a shorter distance means the cable will travel less. SOme levers even come with a system allowing the calbe anchor point to be moved realative to the pivot to change the amount of cable pull.

But since there is no 'standard' it is really down to comparisons - if you have a lever you know works well with cantilevers or caliper brakes, then it is 'short pull,' and one that has a condiderably larger (like 1.5X or 2X) distance between pivot and cable anchor point is a long pull lever (or vice versa).