Marine Plywood Glue
Marine plywood is bonded together with a waterproof glue superior to that used in exterior plywood.
Exterior Plywood Glue
Exterior plywood layers are stuck together with a lower-grade glue that is further compromised by the voids between the layers. It is often water-resistant instead of waterproof.
Marine Plywood Voids
This type of plywood has a minimal amount of voids or spaces between its core layers. This enhances its strength and reduces its susceptibility to rotting because there is minimal space for moisture to become trapped between layers.
Exterior Plywood Voids
The exterior grade has many gaps and voids between layers that are highly visible when the wood is cut. The outside layer is often sealed to help prevent interior rotting caused by moisture, but this is not considered bringing it up to marine plywood quality.
Common Uses for Marine and Exterior Plywood
Marine plywood is almost exclusively used for boat construction. Exterior plywood is normally recommended for projects that will have little or no exposure to moisture.