We experience pain with this same complexity. Pain is only one aspect of our life and our living, no matter how overwhelming it may be at times. Pain is the physical aspect of our life. Suffering is a way of experiencing ourselves and our world. Suffering is the painful consciousness of that within our world which is not what we expect it to be.
Human pain is the physical marker of that suffering.
Pain is always part of suffering but it is never equal to suffering because it is possible to accept a certain level of pain in order to reduce one's or society's suffering. Pain is not always equal to suffering but when suffering is present so is pain. Our choice of pain is tied up with our choice of suffering. Sometimes we face the pain of a situation in order to reduce the suffering present in it. A pain-free spirituality is impossible.