Google engineers developed performance max to help novice advertisers access all the available assets within one campaign.
Although this makes the campaign setup and configuration less complicated, it can deliver mixed results.
Performance Max serves ads on Youtube, Display, Search, Discover, Gmail, Maps, and local ads.
Although it sounds nice to have access to all of those assets within one campaign, Google has also simplified the reporting making it harder to know what works and doesn’t.
Smart Shopping is a mixture of standard Shopping with display ads integrated.
When using Smart Shopping, you are not getting visibility on Youtube, Search, Discover, Gmail, Maps, and local ads.
We typically like all the control we can get with reporting independent of that asset, which is why we strongly prefer Standard Shopping.
Standard Shopping is similar to Smart Shopping but doesn’t have integrated display ads.
When Smart Shopping launched, we were not impressed that they suppressed the visibility of search terms, so we continued to run Standard Shopping with an independent Display campaign.
Beginning in June 2022, Google will start converting the Smart Shopping campaigns to Performance Max, and if not configured correctly, you can see poor results.
For now, we intend to stick with Standard Shopping and layered Display Campaigns.
Hope that helps.