1. SLAs and Uptime Guarantees
This is the sharpest line between the two products. OpenAI.com's API terms do not include a formal uptime SLA for standard API users. The platform targets high availability, and in practice 2025-2026 saw monthly availability in the high 99th percentile range — but there is no contractual commitment, no SLA credit mechanism, and no defined response time for incidents.
Azure OpenAI Service carries Microsoft's standard Azure SLA: 99.9% monthly uptime, with service credit provisions (10% for <99.9%, 25% for <99%, 100% for <95%) that kick in automatically for qualifying subscriptions. For regulated industries or any application where downtime has a financial or legal cost, this difference alone can determine which product you are permitted to deploy.
For context: a 99.9% monthly SLA allows approximately 43 minutes of downtime per month. An OpenAI production incident that runs 2 hours costs you nothing contractually on OpenAI.com but would trigger SLA credits on Azure. Whether the credit matters less than the hours-of-downtime depends on your application — but the contractual protection is real and auditable.