The difference between manual and automatic cars is that manual cars use manual transmission whereas automatic cars use automatic transmission. In a manual car, the driver is responsible for shifting the gears as the car's speed changes, but in an automatic car, changing gears happens automatically.
Since a car with an automatic transmission changes gears automatically, the driver has less work to do than in a car with a manual transmission.
The simple difference in mode of transmission in the two types of cars causes many other variations as well. Over the long run, a car with a manual transmission requires fewer repairs. Even when repairs are needed in cars with manual transmissions, they are usually less costly than repairs on an automatic car. In addition, manual cars tend to be more fuel-efficient than automatic cars. Manual cars give drivers more control, but they generally harder to drive, because the driver must be very alert all the time. In stop-and-go situations, the driver of a manual car needs to maintain balance and coordination between the throttle, the clutch and the gears; this is not always easy. Most car buyers these days tend to prefer automatic cars due to their overall ease of use.