Many of us cannot afford to buy a new car out right so therefore require finance to purchase the vehicle. You can chose to have car finance or to have a personal loan to buy the vehicle and the main difference is that with car finance the car does not actually belong to you until the finance is paid, meaning that if you miss payments the car could be repossessed. With a personal loan you can use the money to purchase the car but the loan is directly with you.
If you wish to sell a car that has car finance on it then you will need to settle this in order to do so. With a personal loan you can sell the car at any time. Often you will get a better rate of interest with a personal loan than through a finance company but it may be harder to obtain.
The other option is to lease a car which normally carries a highly monthly payment but often includes servicing and MOTs etc.