A sunroof is an operable metal panel in a car roof that slides back to let in light and air. A moonroof is a similar panel but the difference is it's glass and it can let light in even when closed. The term "moonroof" was coined by Ford in the 70s but is now used generically to describe glass panel inbuilt electric sunroofs in vehicles by all manufacturers.
To use the moonroof in light-only mode, all you need to do is slide back the fabric-covered panel to expose the glass.
"Moonroof vs Sunroof." Diffen.com. Diffen LLC, n.d. Web. 21 Oct 2014. < http://www.diffen.com/difference/Moonroof_vs_Sunroof >