The thing determining it is the danger of overheating -- so paper or wood lampshades tend to come with a lower rating than glass or metal ones. An LED bulb will heat its surroundings according to its actual mains power consumption, not its "incandescent equivalent wattage", so an LED with 20W draw and 100W equivalent shouldn't be a fire hazard in a "max 60W" fitment -- but with LEDs there's the extra consideration that the bulb itself has a reduced lifespan if it overheats itself, which basically doesn't happen to incandescents.

Peter