The race arena will be where you go to race.
The car arena could for car shows, online car shows even.
The event hall could be special races or other challenges like Gymkhana tests and other things.
Power and speed is probably the machine test.
The Museum wil be where you can check out many of the classic and historically significant cars and learn about them.
The GT bank has got me curiouse eveyone knows what a bank is, but how will it fit into GT4 and how will it work will you have a choice of accounts and be able to invest in the manufacturers or what.
The paint shop will be where you can respray your car and maybe even do a bit more than just change the colour.
Tuning world is actually the tuning village and will be where you buy new parts for your cars, it's name points to more than one tunes shop each might have parts that suit a specific type of racing, like a shop for drifting, a shop for road racing and a shop for rally racing components.
Flea market might be an online rading area, maybe you can purchase some rare parts.
Licence centre is self explanitor really, you'll get your variouse licences here, there will probably be a much larger selection of licences that GT3.
Drift contest wil be where you can take part in a D1GP style drift competition.
The parking is very vague, I think it will be like a parking lot which will replace the garage in previouse GT games and you'll be able to check out all your cars there.