From a handicapping standpoint, there is a fundamental difference between dirt and turf races. Whereas over dirt, speed as an individual element of Class will often be decisive; winners of turf races will require more stamina and determination during the final fraction in order to prevail, thus as a handicapping factor, turf and dirt races must be approached with different methods.
Thoroughbred Horse Racing Over the Main Track and Sod
Often, a quick scan of a horse's racing record can reveal its preferred racing surface. From time to time, when horses are trying a new surface for the first time or just switching surfaces, then other factors can be informative.
In such cases, handicappers may find a horse's breeding to be of some importance. For the most part, if the sire of a race horse was an accomplished turf runner; then it too, may have a propensity to win on turf.
Lastly, turf tends to be a kinder surface to the race horses, runners don't get so much dirt kicked in their face; and as opposed to the main track, the inner rail is frequently adjusted in order to preserve the racetrack surface.
Over a synthetic surface... Safely downgrade I-need-the-lead front-runners unless they are the lone or controlling speed, and upgrade the late closers who figure to be in position to finish well. Look for a change in workout distance or speed.
Patient riders do better on synthetic tracks, as do closers, use contenders who will be running the fastest during the final race segment. The better the quality of horses, the more important it becomes to know which horse(s) will control the final segment.
Similar to turf, whenever a horse wakes up on the switch to a synthetic surface, keep an eye out for next time.