The main difference between a grill and a griddle is the cooking surface. A grill uses metal grates that are typically spread about a half inch apart. This allows the heat from the flame to cook the food directly while the grease drips to the tray without making a mess or starting a fire. A griddle is a heated, flat surface with evenly distributed heat that allows for even cooking of thinner foods that should be cooked quickly (like eggs or fried rice). Charcoal grills are popular for barbecue cooking because of the extra flavor that comes from the smoke of the burning wood. Gas grills are a convenient alternative that makes lighting and cooking on the grill faster and easier at the expense of some of the natural smoke flavor.
Lower-priced grills often use chromed steel for the metal grates. Higher-cost options use cast iron or porcelain enameled steel for the grills. You'll also find solid grills that are similar to a griddle but usually have ridges to allow for grease to drain away while leaving beautiful sear marks on the meat.
