What's the fundamental difference?
Grok is a hosted (proprietary, managed) service: xAI operates the infrastructure, you authenticate to an API, and you pay per use. You don't manage servers, GPUs, scaling, or model updates — that's the product. See docs.x.ai for the API and current model details.
Llama is open-weight: Meta publishes model weights you can download and run anywhere — your own cloud, on-prem GPUs, or a managed inference provider. Meta describes Llama models as ones you can "fine-tune, distill and deploy anywhere," per llama.com. You own the deployment, which means you own both the control and the operational burden.
That single difference cascades into everything else: how you pay, who can see your data, how much you can customize, and how much engineering you need.