Christmas movies come in two kinds of flavors: There's the Zany Frantic Slapfest. And there's the Comforting Holiday Heart-Warmer. A simple rule of thumb to tell them apart: The former, like the newly released Four Christmases, appears in theaters. The latter, like the several hundred examples that will play on the Hallmark Channel, Lifetime, and ABC Family over the next month, go straight to cable. But just like Coca-Cola and Coke Zero, a long complex list of ingredients distinguishes them -- and as our holiday gift to you, we've documented them here.