Great question! For a typical B2B SaaS, you typically will have a multitenant deployment in one region. The control plane APIs and data plane APIs will run in the same region. Each new customer will create a logical tenant in your DB but there are no physical data planes created.

For Infrastructure SaaS, it is a bit different. You typically will have different customers provision your infrastructure in different cloud or regions depending on where they have their infrastructure. This leads to having many physical infrastructure deployed in many regions and cloud providers. At the same time, for the user, you need to provide a single pane of glass experience where they can manage all their infrastructure from a single dashboard. This requires a central control plane that is responsible for all the life cycle management operations and it helps to communicate all the metadata back and forth to all the data planes. Things like upgrades, observability, user and tenant management all need coordination with the data planes. This makes the Infrastructure SaaS use case a bit different from standard B2B SaaS. Hope that helps.