One of the major differences between cooking with wood chips and cooking with charcoal is the amount of smoke that each produces. Wood chips, such as hickory, apple wood or mesquite, create more smoke than charcoal, adding flavor to the food. However, for the wood chips to add maximum flavor, food needs to cook for at least 20 minutes. To get the full effect of the wood smoke, you need to let the flame die down, and then cook meat slowly, taking care not to overcook.
When you grill with charcoal briquettes, the process is fairly simple: you put the briquettes in the grill, squirt on some lighter fluid and ignite. If you're using self-starting briquettes, you can skip the lighter fluid. Once the briquettes are hot and the lighter fluid has burned off, throw on the burger or steak and let it cook. Cooking with wood chips is slightly more involved. Dry wood chips, unlike charcoal, will burn quickly and turn to ash. For that reason, you need to soak your wood chips before lighting them, so that they smoke instead of burn. Not only will you get ample heat for cooking, but you'll increase the smoky flavor that makes cooking with wood so appealing.
Sometimes when you cook with charcoal, you might notice a chemical taste in your food, which doesn't generally happen when you cook with wood chips. Some charcoal briquettes have a petroleum product added to help them light faster, or have added coal to help them burn. If you don't use the charcoal properly -- meaning you fail to allow it to burn sufficiently and get hot before you add food to the grill -- you may notice a chemical taste in the food. This is more likely to happen if you use an inexpensive brand of charcoal, especially one labeled "self-starting." If you're concerned about an odd taste in your food, use wood chips instead.
Grilling is one area where it's possible to get the best of both worlds. If you want the heat and slow burn of charcoal and the smoky flavor of wood chips, combine the two. Add a handful of wood chips to your charcoal after the fire has died down, or create a 50/50 mixture for more flavorful grilling. If you're mixing wood chips with charcoal, you don't need to soak them before adding them to the grill. The charcoal will keep the heat high, and the chips will still add smoke for the short time necessary for cooking your food.