>>718973458
Not sure, at least because I haven't done any research on JP's take on it besides knowing the the bottom line. I'll say the knowledge I know on the differences.
Turf looks better but is much harder to maintain and is much easier to do "damage" to if run over alot, horse or person. There is also a difference on the gripping, although thats just a case of getting use to. Wish I knew how rain affected turf.
Dirt can fall apart easily with no maintenance. However, it is very easy to maintain in the US Tracks using some tractors, a water tender, and the proper attached equipment to groom it after each race. And unless the soil is particularly bad, it's easy to set up anywhere. And when it rains, it just means you do the grooming only and no water is used, although the horses will tire out faster from sinking in, but they're already sinking in a little on normal dirt.
The game makes dirt looks bad by making it look dry and dusty. I have no idea if that's how Japs run their dirt tracks.