There is the difference between grades of plywood and grades of veneer. Grades of plywood are made up of veneer grades which are used for covering. For example, plywood covered on the front side with grade B veneer and on the back side with BB veneer will have grade B/BB - the first indicates the highest grade.
Formation of Uncoated plywood SyPly™ plywood grades
B/B, B/BB, E/BB, S/BB, B/CP, BB/BB, BB/CP, BB/C, CP/CP, CP/C, C, covers
View pictures of plywood by grade
Scheme of forming plywood grades from veneer grades *NSH - unpolished plywood surface
4.0, 6.0, 6.5, 9.0, 12.0, 12.5, 15.0, 18.0, 19.0, 20.0, 21.0, 24.0, 27.0, 30.0, 32.0, 35.0, 40.0
sanded, CP/C – sanded on the 1st side, C – not sanded
increased water resistance, water resistant