Google Payments Merchant Center is best understood as the control area for Google-related seller payments, while Google Pay, Stripe, PayPal, and ecommerce integrations handle the actual checkout experience. TLDR: Use Google Pay to make checkout faster, not as a full replacement for Stripe or PayPal. Use Stripe if you want deep ecommerce controls, subscriptions, fraud tools, and clean developer docs. For example, a store with 10,000 monthly checkout visits and a 2.5% conversion rate could gain 25 extra orders from just a 10% checkout speed improvement, if friction is the real blocker. Honestly, it feels like Google has too many payment names for one merchant to remember.