Please take a look at the terms and definitions we use across Cloud Migration Tool's documentation space.
What is a cloud connection?
This is the connection you create with the Cloud Migration Tool to link a Jira Server/Data Center instance with a Jira Cloud site.
What is a migration?
This is the Cloud Migration Tool process of transferring projects and issues from Jira Server/Data Center instances to Jira Cloud sites.
What is a configuration element?
This is an object in Jira's configuration like a project, workflow, custom field, screen, etc.
What is Cloud Migration Tool?
This is the short name we use to refer to Configuration Manager Cloud Migration Tool. That's an app that allows you to migrate projects and issues from Jira Server/Data Center instances to Jira Cloud sites when paired with Configuration Manager for Jira Cloud.