PC steering wheels tend to be better in every way. Ps2 steering wheels are pretty much the same hardware wise to pcs, thats why u can use generic drivers for them. Some companies even make pc drivers for ps2 steering wheels.
Pc steering wheel drivers are updated often. Even Generic drivers give you better responses out of steering wheels the the ps2 games that are programmed for ps2 steering wheels.
Why, because ps2 games are made to suit only so many steering wheels and some are even designed to work with only 1.
Pc steering wheels follow a tighter standard then ps2 wheels. The games are made looser, follow pretty much DirectX sdks and all aspects can pretty much be adjusted inside and outside the games.
If you want to really see the difference try building a wheel for pc from scratch, and build one for ps2 then tell me which is easier to make.