In the US they are the same thing and can be called by either name. In the UK, flapjacks and pancakes refer to two different things. Flapjacks are sweet tray-baked bars made from oats, like oat bars, muesli bars, cereal bars, or granola bars. Pancakes are flat cakes made of thin batter and cooked on one side, then flipped over and cooked on the second side.