What is Play C.E. in Melissa K and the Heart of Gold Collector's Edition?

I bought Melissa K and the Heart of Gold Collector's Edition and started playing, and exiting said it would save my progress. When I return to the game, the main menu offers either "Play" or "Play C.E.", where C.E. presumably means "Collector's Edition" - but what is the difference, and which one did it start me out playing by default? Are they different adventures or different saved games, or...?

I have been to the web site and searched the web but am finding no information about this.