The acronym BWP stands for 'Boiling Water Proof', while BWR grade means 'Boiling Water Resistant' plywood.
The general naming convention used in the industry is that BWR grading is used for marking plywood, while its counterpart BWP grade is used in the case of Blockboards.
Technically speaking there is not much difference between these two terms. The quality tests on BWR grade plywood sheets, as well as BWP grade blockboards are quite similar.
The glue used in the construction of both these types is synthetic plastic resin (phenol formaldehyde) which is considered better than Urea formaldehyde resins used in commercial MR grade plywood sheets.
If a board is marked with BWR it means that it is a waterproof exterior grade plywood, and if it is marked BWP then it should ideally mean that it is an exterior grade waterproof block board.
Both BWP and BWR grades are widely used in the construction of furniture that is likely to get some exposure to water. Hence it is a preferred choice of material for making kitchen cabinets and other kitchen furniture.