Vertical water smokers and offset box smokers are aimed at two separate kinds of barbecue enthusiast. Vertical water smokers provide a small gradation in temperature adjustment, offer a high level of temperature stability, and are set up for burning charcoal only.
Offset box smokers offer a wider range of temperature adjustment, but with this level of adjustment comes more difficulty in maintaining the temperature, as it's entirely unbuffered. Adding to this smoker's ability to adjust temperature is its ability to burn both charcoal and logs, often known in the barbecue world as "sticks," and offset box smokers as "stick burners."
One of the most popular vertical water smokers is the Weber Smokey Mountain. It can maintain a smoking environment of 250 to 350 degrees for upward of 10 hours without the need to add additional charcoal to the fuel pan. To help maintain these temperatures, at the bottom of the smoker are two adjustable air dampers. These dampers control the amount of oxygen allowed to get to the fuel pan: wide open yields the hottest and fastest burn, while closed yields the coolest and slowest.
Above the dampers is the mesh fuel pan, which allows the ash to drop from the coals. Directly above the fuel pan is the water pan, which acts as a damper. It can be filled with water to maintain a 250-degree environment, perfect for pork shoulder or brisket, or covered in aluminum foil to maintain 350 degrees, ideal for smoking a turkey. Above the water pan are two grates spaced out appropriately to allow for airflow around large portions of meat. The lid houses an additional air damper and a thermometer.
An offset box smoker is a standard barbecue grill with a box attached to the side. It is a simple design that routes smoke from the box into the attached grill area. The offset often has an air damper to allow the smoke to flow continuously from the offset to the grill. As it has no water buffer, it is much more difficult to maintain a set temperature. Without steady monitoring, the temperature can fluctuate hundreds of degrees inside the grill. This is less than ideal for a beginner, but with practice and knowledge of different fuels, fluctuation can be minimized.