No, water-resistant is not the same as water-proof.
Water-proofing is achieved by ultrasonically welding plastic panels together to create a watertight membrane - an extremely expensive undertaking that would likely triple or quadruple the price of the Nomad if used for it's manufacture.
Water-resistance means that the item has a higher likelihood of keeping your possessions dry.
The ballistic nylon covering the entire outer surface of the Nomad is not water-resistant and will absorb moisture, but the rubber backing behind it is water resistant to reduce the likelihood that any moisture will enter the internal compartments. The zips are also water resistant and has integrated water-resistant matte zip-tape covering.
Together, they work to greatly minimise moisture entering the internal compartments and damaging your belongings and art - but is only a stop-gap measure between zipping up the Nomad and finding shelter.