Ad Group Settings level
Ad Group Settings level shows data on keywords and negative keywords number, settings (Search Match on/off, dayparting, CPA goal) and targeting (Device, Age Range, Gender, Location, Customer Type) for all ad groups in your account, app, or campaign.
It gives you the full picture and allows to quickly check a few important points in your account. For example:
Whether you follow the best practices and add negative keywords to your discovery campaigns
Whether your Search Match ad groups contain keywords (they should not, as Search Match automatically matches your ad to relevant search terms and is intended to generate new keywords ideas)
Whether your CPA goals aren't too low (low CPA goals limit impressions)
Whether you have all the key audience covered with your targeting
Whether your audience targeting isn't too narrow (with restrictive targeting you may see fewer impressions and may miss out on your key audience users that switched LAT. To deal with that, consider setting up additional ad groups without demographic targeting)
Ad Groups level
Ad Groups level shows performance statistics per ad group for all ad groups you have in your account, app, or campaign (depending on the level you come from).
In order to check a certain Ad Group, click on its name on the dashboard. You will see statistics per keyword for all the keywords included into this ad group.
Near the ad group name, there is Info button. After you click on it, you will see a pop up with settings and targeting info for that ad group.
From here you can also edit settings and targeting for that ad group by clicking on Edit Ad Group button.