As any do-it-yourself drywaller discovers, there are a number of different types of drywall.
Go to your local home improvement store or lumberyard and you'll find that what you thought was "pretty standard" is really only the tip of the iceberg.
Don't let all those different types of drywall overwhelm you! There are different types of drywall compositions, thicknesses, and sizes for different applications and uses.
How do you know what you should purchase? Below is information on the most common types of drywall available to help you make the right decision.
Standard Drywall This is the most common type of drywall (white paper front) and is used for the majority of home improvement and new home interior construction.
Before beginning a project check with local building codes to ensure that they do not specify that certain type of drywall must be used in construction.
Standard drywall is typically sold in either 4'x8' sheets, or 4'x12' sheets.
Which of these sizes you use is dependent upon the size of the space in which you are installing drywall, the number of people doing the work, and the ease of access (in a basement, for example, it may be impossible to turn a corner with a 12' sheet).
4'x12' sheets are difficult for a single person to work with.
My recommendation is to use 4'x12' sheets whenever possible.
It reduces the number of cuts that need to be made as well as the number of joints that will need to be finished.
Standard drywall is also sold in a variety of widths - 1/4", 3/8", 1/2", and 5/8".
1/2" is the standard width of drywall, suitable for most interior construction on walls and ceilings.
1/2" drywall is considered acceptable by most local building codes.
1/4" drywall is known as flex-board and often used for curved surfaces.
It is somewhat fragile and not highly suggested for the amateur drywall installer.
5/8" drywall is heavier-duty drywall, suitable for use in commercial settings, high traffic areas, or where some excess insulation or noise control is needed.
In some areas, 5/8" drywall is required by local codes.
Moisture-Resistant Drywall (Green Board) Moisture-resistant drywall is also known as Green Board in reference to the water-resistant green paper used outside the gypsum.
Moisture-resistant drywall is a common type of drywall used for high-moisture areas such as bathrooms & kitchens.
There is no difference from standard drywall except that the paper backing used has a much higher moisture resistance than standard drywall.
Green board is highly suggested for use in bathrooms, damp basements, and can be used in kitchens (especially around stoves and sinks).
It is important to note that green board is not fire-resistant, nor waterproof, but resistant to damp conditions.
Fire-Resistant Drywall The final common type of drywall is Fire Resistant, or FR, drywall.
FR drywall is found most commonly in the 5/8" thick variety.
Special fibers and other fire-resistant materials are added to the gypsum core to create more fire-protection than standard drywall.
Building codes in many areas require the use of Fire Resistant drywall for a number of applications, including:

• Walls separating an attached garage from a living space.
  
• Walls and Ceilings in attached apartments or condos.
  
• Enclosed rooms enclosing furnaces, water heaters, or other fire hazards.
  
• Occasionally, kitchens.
  

There are many other types of drywall as well, including soundproof drywall, paperless drywall, and others, but they are less common and so I won't cover them here.
The best of luck on your drywall project.
Visit "How To Drywall" for more drywall installation instructions.