【Central】 , 【focal】 , 【pivotal】 are more closely comparable when they mean dominant or most important than when they refer to a literal or material point (as a center, focus, or pivot).

【Central】 applies to what is regarded as the center because more important than all the rest in that everything else of the same kind depends on it or derives from it.

【Focal】 implies usually a center that is a focus (as of interest, concern, or significance) or that becomes the point on which or in which every or all attention, interest, or activity is concentrated.

The term occurs frequently in the phrase 【focal】 point which equals focus.

【Focal】 may shift its emphasis and attribute such importance to the thing qualified as to suggest that it deserves to be the focus (as of attention or interest).

【Pivotal】 implies an importance that equals that of pivot (a fixed pin or axis upon which something turns) and suggests that the item so qualified is one on which some larger issue is wholly dependent and that it is therefore cardinal or vital.