Two types of pins are demonstrated in the diagram on the left. White's white-squared Bishop is pinning Black's Queen to the King in an absolute pin. In an absolute pin, the pinned piece (Black's Queen) can't move away, because it would leave the King under attack.
Black's white-squared Bishop is also pinning White's Knight to the Queen. The difference here is that this pin is a relative pin. The pinned piece is able to move, but doing so would bring great harm to his position. Here, if the Knight moves, the Queen would be captured by the Black Bishop.