Actually, I think it depends on the game. With the original VCS, the switches are just 'A' and 'B'. With most games using these to mean "Advanced" and "Beginner", respectively. But, since there wasn't really a standard and the labels can pretty much mean anything.. some game companies made 'A' easier and 'B' harder (working in a progression kinda thing.. from a different point of view).
The case here is that Sears went ahead and actually labelled what most games used.. one as a 'Normal' and one as an 'Expert' difficulty. So when you get one of those off-brand games in the system, 'Expert' may be easier than 'Normal'.