Water-resistant and waterproof

The words are used loosely in marketing and the difference matters. Water-resistant usually means a coated fabric with untaped seams and an ordinary zip. It handles a splash from a paddle and twenty minutes of drizzle. It does not handle an hour of steady rain, and it certainly does not handle being dropped in the lake.

Waterproof means the fabric, the seams and the closure are all sealed, which in practice means a roll-top or a welded zip and taped seams. Dry bags are waterproof. Almost no tackle backpack is.

This is why packs are sold with rain covers and why phones live in a zip-lock bag inside them.

Watch for the word repellent too, which sits below water-resistant and generally means a surface treatment on ordinary fabric with nothing behind it. There is no regulator policing any of these words on a product listing.