This blog post compares two Infrastructure as Code (IaC) automation tools, Atlantis and Terraform Cloud/Enterprise. Atlantis is an open-source tool that allows users to orchestrate Terraform automation through pull requests using comments. It's suitable for small-scale projects and casual usage but lacks scalability and queueing support. Terraform Cloud, on the other hand, provides a specialized CI/CD platform for Terraform automation and is more scalable than Atlantis but offers fewer extensibility options. The post also discusses an alternative to both tools, Spacelift, which offers enhanced collaboration, automation, and controls for IaC development.