Yes!
I suppose it could be fair to claim the burden of proof lays upon those of us who want to make this distinction to argue how and why withdrawing artificial life support is different from adding an intervention that will hasten death since the patient is expected to end up dead either way. I'll think about coming back to make that argument, but now it's a nice day so I'm going to go play catch with my kids.
Ok, I'm going to take a crack at this.
There is a real and significant difference between providing comfort while allowing a disease process to take a patient's life versus taking an action to bring about that death. This can be difficult to wrap our heads around because the difference is not felt by that particular patient - in both cases the patient ends up (ideally) dying a comfortable death - the difference is felt by the physician and their future patients.
First, I'll claim that "passive euthanasia" is a contradiction in terms: it is my position that euthanasia is active.
Euthanasia is taking an action with the intention of bringing about death. Therefore it can not be passive. Now, some will say "you ARE taking an action when you remove an endotracheal tube, thus it is not passive." I would counter that
the intention of removing the endotracheal tube is not to cause death - it is to stop causing suffering. Importantly, removal of the endotracheal tube does not reliably cause death. Many (in my practice, most) patients survive compassionate extubation and go on to die from a process other than apnea.
In cases of euthanasia the intent of the action is to cause death, and the actions taken more reliably cause death. If one wants to argue that it is only the consequences and not the intent of an action that determine its morality, then one opens oneself up to A LOT of responsibility. If you chose to fund your retirement account instead of donating to charity, then in this consequentialist framework you are causing the death of impoverished children by funding your retirement. I reject this.
Second, who is harmed by euthanasia? I argue it's the physician and their future patients. The physician is harmed, because in providing euthanasia they have begun to establish a pattern in their behavior. Causing death is something that they have now willingly done. This may make them more willing to cause death in the future. Their patients are harmed because they now know it's possible that their doctor's intention may be to cause their death. What was previously a possibility that they didn't have to consider is now a legitimate worry, "could my doctor be trying to kill me?"
In summary - withdrawal of artificial life support is different from euthanasia because only the latter requires the intention of causing the patient's death. I chose to not practice euthanasia, while being comfortable providing comfort care at the end of life, because I worry that providing euthanasia could establish patterns of thought and behavior in myself that I do not want established. I also want my patients to be secure in the knowledge that they can trust I am not trying to kill them.