So guys ... what are physics? Everyone says this game has better physics over this another. Explain to me
I think you answered your own question, in a way.
It seems like certain people latch onto certain games because some aspect of how some cars behave hits them right in the pleasure center. With Forza, there are some aspects which favor certain styles of driving, like those who want to take turns as fast as possible, or those who favor American hotrods, and drifters have a field day because drifting is easier in the Forza engine than other games, or real life. Some like the partial damage implementation. I was drawn to it because it offered "endless" possibilities for modifying and race liveries. I say "endless" because there is only room for 350 some odd cars, which runs out fairly quickly if you have many cars race modded and buy periodically from the Auction House. Online play is fairly stable with good pings to most servers.
People are drawn to Codemaster games because of a certain flavor of physics, and a pretty good collision/damage implementation, along with dozens of different styles of racing.
A very few prefer Enthusia for having something over the other console racers, though for the life of me, I couldn't figure out what they were talking about. Just taking turns at slightly aggressive speeds was treacherous because the car almost refused to communicate anything to me with my DF Pro wheel, and as often as not, I mysteriously went off the track.
Some have glommed onto Ferrari Challenge, and it seems developer Eutechnyx licensed the Forza 2 engine and juiced it up with Aegia's PhysX code. They swear they feel some aspects of weight transfer better than the other console racers, and others like braking and tire dynamics they insist is modeled better.
Lots of racers went nuts for PC sims such as the GTR series, rFactor, Live For Speed and iracing which do a nice overall job of delivering precise if forgiving physics to one extent or another. I suspect that's what some of the gripe is over Simbin's GTR series, because I was surprised at how difficult it was to go wrong once you get a handle on the feel of the cars. I suspect that LFS, iracing and Richard Burns Rally are the most finicky and demanding of the PC sims.
And that leaves Gran Turismo. After spending time with Prologue, my once vaunted GT4 felt primitive in comparison. But at the same time, the crazy thing still manages to get most of the aspects of racing right. Mid-engined cars are tail heavy and require power through turns, while rear engined RUFs are downright twitchy. While grip loss is usually rather gradual, it can be abrupt depending on the situation, while it tends to be properly snappy when grip is regained. Street cars lean around turns, and older, taller cars lean quite a bit, realistically so. As Nox mentioned, easing on the throttle can enable you to use the mid-engined cars' tendencies to swing the tail out to take turns more aggressively, though you have to be careful to keep from spinning out. Rear drive cars muscle through turns while front drive cars pull. While at first I thought sports tire equipped cars understeered and bogged a bit too much in turns, recent driving has made me wonder if it's not actually very realistic.
And especially when driven from roof cam, I feel very connected to the car. The view as someone pointed out is centered over the front seat, giving you a sense of balance focused on where you would be in an actual car. You have the benefit of the panoramic view of the track which is evidently very hard to recreate properly with cockpit view, and you also have the benefit of peripheral vision to the sides of the car. While braking is a bit too stable, you can judge braking and gas points in turns very well when you get familiar with the cars, and can get comfortable fairly quickly with how much you can push various cars at different performance levels. When I make a mistake in GT, I usually know why. While it's fairly forgiving, it still requires you to be close to where you should be driving or off the track you go or into another car.
Compared to other games, the story is a little different. For instance, Toca has about the best cockpit view in racing games, though that's because the windshield presents almost the entire field of view, as if your chin were on the dash. There are a very useful range of driver cams, though no roof view, so I felt fairly well connected. Physics did feel a little scripted at times. Collisions were very dramatic and pretty realistic. Unfortunately, the steering wheel implementation was terrible, and I had to fight to get something workable.
Forza and Ferrari Challenge are fairly similar, as they use the same engine. Even the very same vinyls in the livery shop! Forza sports tires have a satisfying grip, though after flinging my Supra around a bit, it seems way too much grip. It also has a weird oversteer tendency with only moderate power sometimes. Jerking the wheel is usually enough to stop a skid and regain grip. Cars won't lean around turns. I don't care for the camera angles, and am forced to drive chase cam in both, though it's far worse in FC because the view is way too low, and I don't like the cockpit view at all. While some rear-engined Porsches are downright treacherous, mid-engined cars are too well mannered and easy to drive. Ferrari Challenge, featuring only Ferraris on racing tires, is much better balanced and sim-like, though with the same oversteering flaw. But you have to keep in mind that the cars are almost all mid-engined and throttle around turns carefully or you'll go spinning. Because of the camera views in both, while I feel pretty well connected to the cars in both, taking turns is kind of a roll of the dice for me, and this is where racing really matters. So many times in FC, I'll smack right into the wall in a turn on Monza because I'm fishing for the proper way to tackle it, making it as frustrating as it is fun.
While the first GTR was a mess for me, GTR Evolution was a pleasant surprise when I got the feel down. While it has pretty demanding if forgiving PC sim physics, it doesn't take long to come to terms with its various cars, and you should be able to push your car competitively as you get used to the dynamics of racing. Tire grip, weight shifting, tuning, accelerating and braking feel quite lifelike, as far as I can tell, having never driven a real race car. While I also bought rFactor, my DF Pro wheel died thanks to my current PC - soon to be replaced, so I couldn't compare the two. I won't mention Enthusia because, try as I might, I felt the least connected to the car and in control of all the games I've played. Nothing worked, so I'm pretending it doesn't exist - sorry, Enthisiastics.
Gran Turismo 5 Prologue and Toca seem to be right in the middle of it all, a nice balance of forgiving behavior with a healthy dose of realism. As VIPERGTRS01 mentioned, coming from a PC sim to Prologue felt pretty smooth and similar. You could tell that it was a console sim rather than a more finicky PC sim, but the differences are surprisingly thin. With each GT game, Kaz and his team drew closer to reality, and Prologue is very close to real life. It makes me VERY anxious to get my hands on GT5 itself, and see what secrets Kazunori-dono has been keeping from us.
And yes, I too would LOVE to be a race car driver.