The side 69 is where you both lie down facing each other, with your heads in each other's crotch. You then take each other's penis's in your mouth and go for it! The Top and bottom 69 is a variation on the theme where one guys lies on his back and the other guy lies down on top of him. This can be a bit of an awkward position as the guy on the bottom cannot always get enough leverage to suck the other guys' cock.
And it is also penetrates quite far down into the throat. The classic lying down position is where the guy receiving head lies down on the bed and the other guys kneels above him fucking his face.
