When placing a piece vertically with finesse, players have to rotate a piece either clockwise (CW) or counterclockwise (CCW) to place it to a specific column with minimal inputs. Finesse is most important and strictly adhered to in 40 line sprints where players hard drop all pieces, where the rotation state that the piece is in does not matter.
However, when you would like to spin in a piece, the piece orientation matters, i.e., whether you have rotated your piece CW or CCW. When placing a S or I mino vertically, for example, in column 1, the resulting orientation of the piece may not be compatible with the spin you would like to perform.
This is where situational finesse comes in. This page lists input sequences that you could use when you would like to place piece at a specific column with an alternate orientation compared to when you would place it with original finesse.
At the moment, situational finesse is purely theoretical.
Original finesse has two ways to place the piece on this column which covers the alternate orientation.
2 ways to do this too