What are the differences among Internal storage, external storage, sd card and removable storage?

Question

From the official documentation:

Using the External Storage

Every Android-compatible device supports a shared \"external storage\" that

Answer 1

From the Developer docs

All Android devices have two file storage areas: "internal" and "external" storage. These names come from the early days of Android, when most devices offered built-in non-volatile memory (internal storage), plus a removable storage medium such as a micro SD card (external storage). Some devices divide the permanent storage space into "internal" and "external" partitions, so even without a removable storage medium, there are always two storage spaces and the API behavior is the same whether the external storage is removable or not.