Actually the "Blue Drawer" is for single action lists and and "little lists" are projects. There is a difference.
As I understand it:
Every action in a single action list is considered a "Next Action" (not including nested or pending stuff). If you have 20 actions in a single action list and choose to filter by "Next Action", you'll see all 20.
A project can be either sequential or parallel. EITHER WAY, only the top action listed in a project is considered a next action. If you have a parallel project with 20 actions and choose to filter by "Next Action", you'll only see the first one on the list.
You can have multiple available actions on a project, but only one next action. All available actions on a single action list are next actions.