What's the difference between waterproof and water-resistant for dog jackets?

Testing-focused write-ups we read distinguish coats with a measured waterproof rating (for example, the 10,000mm figure cited by treelinereview.com for several full-coverage shells) from lighter water-resistant coats that bead off drizzle but can wet out in a sustained downpour. If you live somewhere genuinely rainy, reviewers steer you toward seam-quality shells over thin slicker ponchos.