Though the builders know the difference is in the trademark drywall is sheetrock far the common man as the trademark has been well established.
Difference between sheet rock and dry wall.
All sheetrock can be called drywall but not all drywall can be called sheetrock.
However due to its tremendous popularity people mislabel all sorts of drywall as sheetrock.
Think of it like this.
To refer back to the kleenex versus generic brand analogy sheetrock is a name brand much like kleenex and drywall is the same product just without a brand name.
Gypsum powder makes up drywall.
It is finely ground and then pressed in between two thick pieces of paper.
Drywall is made of a few different materials but most commonly it is made from gypsum which is a sturdy yet lightweight rock that provides versatile uses when ground up into a powder.
This creates a board or a thin sheet.
The major difference between sheetrock and drywall is that only the us gypsum company can call their product sheetrock no one else.