Same company, same vendor database
The single most important fact about this comparison is that The Knot and WeddingWire are the same company. The Knot Worldwide owns both, and they draw on one shared database of wedding professionals. A photographer listed on The Knot is almost always listed on WeddingWire too, often with the same reviews and the same contact form behind the scenes.
That means the choice is not really about which has more vendors. It is about which interface you prefer and which extra features you want. The Knot is positioned as the flagship couple-facing brand: registry, planning checklist, content library, and website builder all wrapped around the marketplace. WeddingWire grew out of vendor reviews and still feels more review-first, which some couples prefer when they are deep in vendor research.