JAMStack vs Serverless

Sorry a basic questions:

  1. What is the difference between JAMStack and Serverless?

The pre-rendered generated HTML is served from CDN in order for it to qualify as JAMStack, served from Edge.
2. How about APIs - Does the APIs need to be located in multiple regions too?
3. Are Netlify Lambdas available on EDGE by default?

Also, any link to a resource explaining difference between JAMStack and Serverless would be appreciated. Please suggest.