Sorry for this very newbie question...

I was looking at fare information on EF and the system gives a list of fares. The price on these fares is often lower than what I get when I go directly on the operating carrier's website. Does this mean that the fares EF displays are bookable? If so, how do I book them, since the operating carrier's website does not show these fares. Would I have to call the airline directly?

Thanks!