A geomantic figure is fully described by its four rows, each holding one point or two, and that description is independent of anything the tradition reads into it.
The pattern
Fortuna Major is double, double, single, single, reading Fire, Air, Water and Earth from the top down, for six points in total. The two heavy rows sit above the two light ones. In the common reading a single point marks its element active and a double marks it passive, so the figure has an active lower half under a passive upper half.
Flipping every row
Change each row from single to double and from double to single and Fortuna Major becomes Fortuna Minor. This is the one pair in the sixteen where the two partners already carry names that announce the relationship, greater and lesser fortune, and it is the clearest illustration of what the operation does.
What the pairing does and does not mean
The two figures are not read as good and bad. The traditional distinction is between a strength that comes from within and holds, and a strength that comes from outside and does not, which is a distinction the point pattern makes visible: the heavier rows are uppermost in one and lowermost in the other.
Beyond that, the pairing is arithmetic. Sixteen figures form eight such pairs because inverting every row maps the set onto itself. The atlas records the planet, sign and element for this figure separately; those came from the astrological tradition, differ between handbooks, and were never derived from the points.