» Terraform vs. Boto, Fog, etc.
Libraries like Boto, Fog, etc. are used to provide native access to cloud providers and services by using their APIs. Some libraries are focused on specific clouds, while others attempt to bridge them all and mask the semantic differences. Using a client library only provides low-level access to APIs, requiring application developers to create their own tooling to build and manage their infrastructure.
Terraform is not intended to give low-level programmatic access to providers, but instead provides a high level syntax for describing how cloud resources and services should be created, provisioned, and combined. Terraform is very flexible, using a plugin-based model to support providers and provisioners, giving it the ability to support almost any service that exposes APIs.