What is the difference between Water-proofing & Damp-Proofing membrane?

The main function of both coating / membrane / system is minimizing the travel of water through a substance. But there is some difference is there as discussed below.

Waterproofing is a treatment of a surface or structure to prevent the passage of water under hydrostatic pressure. This system may be placed on the positive or negative side. Damp-proofing is a treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure. …As per American Concrete Institute (ACI 515.1).

Another definition of damp-proofing given in ACI Special   Publication 192    is:

"Treatment of concrete or mortar to retard the passage or absorption of water, or water vapor, either by application of a suitable coating to exposed surfaces, or by use of a suitable admixture or treated cement." As these definitions indicate, damp-proofing will only reduce the rate of transmission of water through concrete.

Positive side - the system is placed on the same side as the applied hydrostatic pressure and negative side - systems are placed on the side opposite to the applied hydrostatic pressure.

When waterproofing is used?

 Ø  Waterproofing is normally used to prevent leakage of water into, through, or out of concrete under hydrostatic pressure.  

 Ø  If freezing and thawing conditions exist, as in above-grade applications or if the water is carrying aggressive chemicals which attack reinforcing steel or concrete, then the waterproofing barrier will be used to prevent leakage into the concrete.

 Ø  If a dry surface is required for applying coatings, then waterproofing could be used to prevent moisture from leaving the concrete.  

 Ø  Waterproofing is also used to minimize unsightly carbonates or efflorescence. IRC (The International Residential Code) says, Waterproofing is required only in areas where a high water table or other severe soil-water conditions are known to exist.

When damp-proofing is used?

 Ø  A damp-proofing barrier system is used to perform the same functions as a waterproofing system but cannot be used to protect against water under pressure.

 Ø  A drainage system may be required to prevent the development of a head of water. Damp-proofing is a low-cost system because the material thickness is relatively low and minimum surface preparation is required.

 Ø  A damp-proofing barrier system   will   minimize water vapor transmission through concrete if the concrete will not be subjected to a continuous or even an intermittent head of water.

 Ø  IRC (The International Residential Code) says that any concrete or masonry foundation walls that retain earth and enclosed interior spaces and floors below grade shall be damp proofed from the top of the footing to the finished grade.

Many thanks to www.google.com, don3.com, etc from where the details are taken.