Mostly geography! Here in the U.S., the term flapjacks is a colloquial or slang name for pancakes, mostly used in the South. (Sorry friends, if you're looking for a soft flapjack recipe, this isn't it.) However, in the U.K. flapjacks refer to baked oat bars (also called an oat slice), and is similar to what we think of as granola bars; that's what we're making here.