Preview vs. Test vs. Publish

Preview allows you to see how a configured nudge (tooltip, in-app message, coachmark or badge) will appear on a selected test device.
Test mode is used to display the configured nudge on a set of selected test devices after specific context or conditions are met by the users on those devices.
Publish means launching the campaign for all the targeted users, making the configured nudges visible to end users.
It doesn't check for the set context to be met. In other words, it shows you the nudge as it would look, but it doesn't take into account whether the conditions or criteria for displaying the nudge have been satisfied.
Test mode considers the context, which means the nudge will only be shown to the selected test devices on their devices if they meet the specified criteria or conditions.
This is the live deployment of the nudge to the broader audience, and it occurs once the specified context or criteria are met on the end users' devices.
Preview is typically used for internal testing or to visualize the appearance of a nudge without affecting real end users.
Testing is a crucial step to ensure that the nudge is displayed correctly to the intended users under the right circumstances. This is also typically used for internal testing
Publishing the campaign is the final step where the nudge is presented to all users who meet the predefined conditions, and it is part of the active user engagement or marketing strategy.
In summary, Preview is for internal testing and visualization, Test ensures the nudge is shown to the right users when specific conditions are met, and Publish releases the nudge to the broader audience for whom all the pre-set criteria are satisfied.