Woodburning stoves and fires are only designed to burn dry logs. Wood burns best on a small bed of ash so you tend to burn directly on the base of the stove. Multifuel stoves are designed to burn smokeless fuel as well as wood. To burn smokeless fuel, you need more air under the fire than wood, therefore you have a grate within the stove or fire for the air to come up through. Smokeless fuel also produces more ash, so you usually have an ashpan to make it easier to remove the ash.