Plywood grading can feel like alphabet soup until you know what the letters actually protect against.
MR (Moisture Resistant) plywood is bonded with a resin that can handle occasional dampness — spills, humidity, the odd splash. It's the right call for bedroom wardrobes, living room units, and most furniture that stays indoors and dry.
BWP (Boiling Water Proof) plywood is built for sustained water exposure. The bonding resists prolonged moisture without delaminating, which is why it's the standard for kitchen base cabinets, bathroom vanities, and any exterior-facing woodwork.
The simplest way to decide: if the piece will occasionally get damp, MR is fine and saves you money. If it sits somewhere that stays wet or humid for long stretches, spend the extra on BWP — replacing a swollen cabinet later costs more than the grade upgrade would have.