Vented fireplaces have an exhaust and an open firebox for the intake. Vented fireplaces can be used with gas and or wood burning fires. Vented fireplaces require a hearth because they are not sealed with a glass front. Vented fireplaces put out great heat. 

Some people prefer direct vent fireplaces because the gas fumes stay contained to the fireplace and outside. Also you cannot reach in the firebox and touch a flame with direct vent fireplaces.