There is difference between "currently playing" and "games I need to finish" just like there is difference with "plan on getting" and "to buy list".
Currently playing is usually one game to, say, five games that I'm actively playing right now. Every day, every week. And for that I can usually answer easy.
Games I need to finish on the other hand.. I'm not playing them, but I know I want to play and finish them sooner or later. Maybe. I may pick it up again on a whim if I feel like it, and if I can - or not. There is a huge difference. And the answer is also a lot more difficult. The list is just so huge. I can't even remember all of those games at the same time.