The AO lighting code is easy to remember, because it stands for ODALS, which in turn stands for "you know, that flashy light thing." Or in official language "omni-directional approach lighting system."
ODALS consists of a sequence of five flashing lights, 300 feet apart, leading in towards the runway. They flash in sequence, leading the eye towards the runway, then the two runway identification lights at the threshold flash together. The effect is like the flashing squiggly arrow on a neon sign luring you into a strip club or a lousy restaurant.
As I understand it, the difference between ODALS and SF is that ODALS is the very specific seven light system in the 1500' before the runway, while SF can refer to any sequenced flashing light system.
I love the way it looks out the window in the snow when it's so white that you can't tell if you're in cloud, in staring into falling snow, or parked inside a snowdrift. And then you see the little flashing lights and the runway magically appears in front of you.