"Historically, sunroofs have been opaque and open to the air to allow the sun to shine directly into the vehicle, while moonroofs have generally been transparent or semi-transparent and designed to remain closed while allowing muted light to penetrate the vehicle.

Variations have become the norm and often combine the features of the Sun and Moon types into a single device. It is not uncommon to see tinted glass that can retract fully like a traditional sun roof, remain closed like a traditional moon roof, or tilt to allow for airflow."

-- Wiki