Three different things are casually called "the backup." They contain different content, they are retained differently — and using the wrong one in a crisis wastes the time you do not have.
The environment backup — a daily capture taken by the platform. Broader in content than the maintenance snapshot. The maintenance snapshot — taken during daily maintenance, and the artefact you typically work with for restore and migration. The artifact snapshot — a snapshot of application artefacts, which you can take on demand, download and import elsewhere. The vehicle for Module 5's migrations.
THE ENVIRONMENT BACKUP CONTAINS ARTEFACTS THE MAINTENANCE SNAPSHOT DOES NOT. Know which items those are for your business process. They are the ones that surprise people during a recovery — which is the worst possible moment to be finding out.
What is in a snapshot structurally: the artefact files, and the definitions describing them.
And the table this lesson exists to produce. Restore after an incident. Migrate to another environment. Refresh test from production. Recover a deleted artefact. Which mechanism, and why.