Scooter of 125cc liquid cooled what is the difference between carburater and injection motor which is better

First things first...are you talking about fuel injection or oil pump injection. I don't know of any 125 scooters with fuel injection. The carburator regulates the fuel/air mixture into the motor. More fuel - faster the motor runs. The injection motor (oil pump) is used on 2 stroke motors. 2 stroke engines need oil added to the fuel, to lubricate the piston/rings/cylnder. Off road compitition bikes, the oil is pre-mixed in the gasoline before putting it in the gas tank. 2 stroke street bikes and scooters have a seperate oil tank for convienence. As the engine speeds up, the injection motor pumps more oil to mix with the fuel. As for your question - which is better? They're two different things. It's like asking which is better, apples or oranges.

Fuel injection is always preferable, assuming both bikes are otherwise similar. FI uses an electronic brain to determine fuel/air flow under different circumstances. It generally offers better power under a wider array of conditions, and better fuel economy. On an engine of small size like this, you may not notice a huge difference, but then again why get the most out of the engine?