Maitreya, on the left, is the bodhisattva who will be the next Buddha to appear in this world. His hands are held o his heart in the gesture of teaching, or of "turning the wheel of life".
Eleven-Faced Avalokiteshvara, on the right, is the bodhisattva of compassion. He took a vow to save all beings from suffering, but when he realized the magnitude of the task his head exploded into countless pieces.
The Buddha reassembled his body into a more powerful form having eleven heads.