BWR – Phenol formaldehyde synthetic is used for glueing the plies together. This is a synthetic plastic resin.
MR – Urea formaldehyde resin is used for bonding the plies to each other. UF resin is not considered to be very eco-friendly.

Some shopkeepers erroneously (or is it deliberately?) inform customers that Marine plywood is the same as BWR grade waterproof plywood. This is simply not the case. Marine plywood is a much better kind of plywood in which unextended (undiluted) phenolic resins are used for glueing the plies together, which makes it stronger. Marine ply is meant for extreme cases of exterior use, such as for making boats and ships or other river equipment, where the plywood is sure to become and remain wet for a prolonged duration.