Center Opt-ins are completely separate from Interest Opt-ins and both serve a different purpose.

A Center Opt-in happens when a constituent registers to your site from a center-level application such as a Survey or TeamRaiser. If the constituent elects to receive email communication from your organization when they register, then they are opted in to site-wide email and also Center emails. In this way, Center Opt-ins are more seamless than Interest Opt-ins.

Interest Opt-ins can be used from a site-wide level, or within a center. Interest Opt-ins are configured within the application where constituents are registering, such as a Survey or TeamRaiser. You can add a Hidden Interest Update Question that constituents can not see which will opt them in to an interest.

In summary, Center Opt-ins occur when a constituent action is taken from a center and they elect to opt in to communications. An Interest Opt-in occurs when a constituent takes an action from a specific form that contains a Hidden Interest Update Question.