Each digital advertising platform is a little bit different, but the general format for Google and Facebook ads is three-tiered.
The first tier is your account, which manages all of your billing information for your campaigns. The second tier is campaigns, each of which has a budget allowing you to allocate different amounts of money to different tests that you wish to run. The third and final tier is ad groups. Each ad group contains a number of different ads, but has consistent targeting.
These different tiers allow you to allocate budgets to different tests and see consolidated or detailed reporting that you will need to refine and optimize your audience targeting and ad content.