When should an advertiser use an app extension instead of an app promotion ad?
- With keywords intended to direct users to the mobile website, but still give the option to download the app
- To run your ad on both Search and Display
- To re-engage with users who have already downloaded the app
- With keywords intended to drive app download, but still give the option to visit the mobile website
App extension is a good way if you want to direct users to your mobile website but also leave a possibility to download an app.
App extensions allow you to link to your mobile or tablet app from your text ads. People click either on your ad headline to go to your site, or on the link to your app. App extensions are a great way to provide access to your website and your app from a single ad.
Read more here: https://support.google.com/adwords/answer/2402582