Yes, it's still a resignation, but if the employee gives two weeks notice and the employer releases them immediately and does not pay out the notice, it's possible in many states for the employee to receive unemployment for part or all of the notice period. I cannot find anything specific to Illinois to say one way or the other. IL has a one-week notice period but they may conceiveably be able to collect UI for the other week.
If the company wants to ensure that the employee does not collect UI but does not want them to work out their notice, the way to achieve that goal is to pay out the notice period.

