One thing that could make a BIG difference here is the fact one is a PC and the other is notebook. The ATX Form Factor standard for PCs calls for the power supply to deliver +5Vsb standby voltage to various parts of the motherboard, to include the front panel power switch, RAM (for hibernate modes), and various devices (keyboard, mouse, NIC) for such "Wake on...". commands.
A notebook, however, does not have this standby voltage because obviously, it would run down the battery if the charger is not plugged in.