The defining factor is the internal wave count of the patterns.
Leading diagonal triangles subdivide into a 5-3-5-3-5 wave count where waves 1,3 and 5 are normal 5 wave impulsive moves. The key factor here is that wave 4 overlaps wave 1.
Leading diagonals can only appear in the waves 1 or A positions.
Ending diagonals can only appear as 5th or C waves and subdivide into 3-3-3-3-3.
Horizontal triangles are corrective consolidation moves and subdivide 3-3-3-3-3....these can only appear in the 4th and B wave positions.
