Mobile Display Network campaigns allow you to reach people using apps similar to yours. Showing your ads to users who are likely to be interested in apps (those who already use the apps) increase the effectiveness of your ads; Increasing the number of downloads can also increase your app's ranking in the store.
Mobile Search campaigns help you reach people who are already searching for apps like yours on their mobile devices. These campaigns are an excellent way to get your app discovered by people who are most likely to be interested.
App promotion ads (formerly "click-to-download" ads) are the easiest and most effective way to increase downloads. In this ad type, most of the customization is done for you. You can run these ads on the Search Network and the Display Network using the App/Digital Content Ad template.
App/digital content ads on the Search Network may only appear where paid app content is served to users.
App promotion ads direct users to the Google Play Store or Apple App Store, making it easier to download your app.