The double glazed glass is two or more monolithic glass sheets, separated from each other by dehydrated air chambers. The separation between the 2 glass is done by means of an aluminum separator, inside which a desiccant product is introduced, and the tightness is ensured by a double perimeter seal. The interest of this type of glass is its better thermal and acoustic insulation. If you want to give good noise insulation, it is necessary to use glass sheets of different thicknesses to avoid possible resonances.
The monolithic glass does not have any treatment. It is the common glass. It is called "annealed" or "float", terms that refer to its manufacturing process.
Float glass or monolithic glass consists of a sheet of glass manufactured by floating the molten glass on a layer of molten tin. This method gives the glass a uniform thickness and a very flat surface. It is also called flat glass.