No. Each expert is not separately trained, and while they may store different concepts, they are not meant to be different experts in specific domains. However, there are certain technologies to route requests to different domain expert LLMs or even fine-tuning adapters, such as RouteLLM.
First off, they are basically completely different technologies, so it would be disingenuous to act like it's an apples-to-apples comparison.
But a simple way to see it is that when you pick between multiple large models that have different strengths, you have a larger amount of parameters just to work with (e.g. Deepseek R1 + V3 + Qwen + LLaMA ends up being 2 trillion total parameters to pick from), whereas "picking" the experts in an MoE like has a smaller amount of total different parameters you are working with (e.g. R1 is 671 billion, Qwen is 235).
Many models that use test time compute are MoEs, but test-time compute is generally meant to refer to reasoning about the prompt/problem the model is given, not about reasoning about which model to pick, and I don't think anyone has released an LLM router under that name.
