Every year, thousands of new sellers make the same expensive mistake. They pick a platform based on what they've heard from friends, watched in YouTube tutorials, or read in a quick comparison article — and six months later, they're either paying fees they didn't budget for or rebuilding their entire business from scratch on a different platform. The decision between these two giants isn't just about where you list your products. It's about what kind of business you're actually building — and that distinction matters more than most first-time sellers realize. They're Not Actually Competing at the Same Thing This is the part that most comparison guides gloss over. Amazon and Shopify are fundamentally different tools solving fundamentally different problems. Amazon is a marketplace. You're not building a store — you're renting a shelf inside the world's largest retail warehouse. Over 2.45 billion visits flow through Amazon every month, and those visitors are already there to buy. You don't need to bring them.…