Lesson
White to move. Main line: 1. Bb3 Kd4 2. Ke2 Kc5 3. Kd3 Kb5 4. Kd4 Kc6
The bishops work as a pair on adjacent diagonals. Placed side by side they cut the board in half, and every time they step forward together the half the enemy king lives in gets smaller.
The king is the piece that actually forces matters. The bishops take squares; the king takes the opposition and pushes. Trying to mate with the bishops alone gets nowhere — this is a three-piece technique.
The tablebase gives mate in 31 from here, comfortably inside the fifty-move limit. That is the practical difference from bishop and knight: two bishops need no special corner and leave plenty of margin.