Red Hat Ansible Automation Platform 2 comes with new components and new names for tools you already know.
Because some of you might be confused by all that new terminology (I know I was), I'll try to shed some light on some of those names:
Ansible Content Collections, or "collections" in short, are the new way Ansible distributes content, such as modules, roles, and plug-ins.
Red Hat Ansible Certified Content Collections are specific collections certified and maintained by Red Hat and its partners, such as redhat.satellite or amazon.aws.
Ansible automation hub is the distribution platform that hosts the Red Hat Ansible Certified Content Collections. Red Hat hosts this platform at https://console.redhat.com/ansible/automation-hub. In a way, Ansible automation hub is similar to Ansible Galaxy but for certified and fully supported collections (subscription required).
private automation hub is the distribution platform that you can install inside your organization. You can synchronize the Red Hat Ansible Certified Content Collections from Ansible automation hub to make them available to your internal projects.
The platform can also host your custom collections, collections from Ansible Galaxy, and automation execution environment container images.
automation controller is the new name for Red Hat Ansible Tower.
As a side note, I tried to use the official capitalization for those names. So that's right, "private automation hub" and "automation controller" are all lowercase.