Vented
Vented fireplaces are the most common types of fireplaces. Normally, these are fireplaces that were originally used for burning wood logs. They have a chimney which can not be capped off or with a closed damper while in use. Vented fireplaces give less heat than vent-free as it escapes through the chimney, although they are more realistic and lifelike due to the flame being able to touch the logs directly.
Vent-Free
Vent-Free fireplaces are less common than vented, although they are easier to install and maintain. The flames do not touch the logs directly, which results in no harmful fumes being created. This removes the need for an operating chimney. Due to their being nowhere for the heat to escape, vent-free provides more heat than vented fireplaces.