Understanding the different Go SDKs

Gemini API
1

I can find four different Go SDKs

  1. google/generative-ai-go – Gemini API only, can list models
  2. … go/vertexai/genai – Vertex AI only?
  3. …/genai – Cannot list models, can switch between Vertex AI and Gemini API
  4. cloud.google.com/go/ai – ???

What are the differences between the different Go SDKs and why can I not use the “genai package - google.golang.org/genai - Go Packages” SDK to obtain a list of models?