A griddle pan is a stove top pan similar to a frying pan but with some distinctive features, a griddle plate has raised ridges which emulate grill cooking and they also tend to be much heavier than standard pans as they are often made from heavy materials like cast iron.
The raised ridges of a griddle pan infer heat directly to the surface of the meat, heat is also applied indirectly by radiating from the valleys in between the ridges. A griddle therefore gives you all the benefits of grilling but with the convenience of stove top cooking. Often meat is seared just after being cooked in another vessel, this gives the meat the distinctive lines that only grill cooking can achieve. Cooking using a griddle plate at high temperatures gives meat a distinctive roast flavour.