If your game is playable from start to finish, it is not a demo version. If you want to convince people to pay for your free game by giving them extras or deluxe game play, this does not make your "public" version a demo version.
The pricing options can be utilized this way, but it is misleading and confusing.
And more interestingly for the publisher, the game will not appear in the free games section and it always has that nasty price tag displayed. Even if you offer your public version as a "demo".