http://en.wikipedia.org/wiki/Cookware_and_bakeware"....Grill pans are frypans that are ribbed, to let fat drain away from the food being cooked......"
"...Griddles are flat plates of metal used for frying, grilling, and making pan breads (such as pancakes, injera, tortillas, chapatis, and crepes). Traditional iron griddles are circular, with a semicircular hoop fixed to opposite edges of the plate and rising above it to form a central handle. Rectangular griddles that cover two stove burners are now also common, as are griddles that have a ribbed area that can be used like a grill pan....."
http://www.bbc.co.uk/food/glossary/g.shtml?griddle"Griddle A flat cast-iron pan traditionally used for breads and scones. More recently griddles tend to have a ridged surface and are used for cooking vegetables, meat and fish. It tends to be thought of as a healthier method of cooking as the fat from the meat drains away down into the grooves."
Bartleby.com
http://www.bartleby.com/61/82/G0268200.html"griddle - A flat metal surface, such as a pan, that is used for cooking by dry heat."
Google Images:
http://images.google.co.uk/images?q=griddle+panhttp://images.google.de/images?q=grillpfannehttp://de.wikipedia.org/wiki/Pfanne"Steak-Pfanne auch Grillpfanne genannt, ist meist aus Gusseisen und haben einen gewellten Innenboden, mit dem sich schnell und optisch ansprechend durch die Grillstruktur braten lässt."
