What is the main difference between withholding life-sustaining treatment and withdrawing life-sustaining treatment?

Withholding life-sustaining treatment refers to the decision not to initiate a medical intervention that could prolong life, while withdrawing life-sustaining treatment involves stopping an intervention that is already being administered. Both decisions are often made in the context of patient autonomy and quality of life considerations, but the key difference lies in the timing and context of the treatment being addressed. Withholding is about not starting a treatment, whereas withdrawing is about discontinuing one that is currently in place.