What is the difference between a smart list and a smart campaign that creates a list?

The smart campaign de-duplicates email addresses, skips marketing suspended and unsubscribes.

 

A smart campaign referencing a smart list often has less marketable leads.

 

The reference to "The smart list included members that it shouldn't." may arise from its own filters.

I can review that for you. The only information required would be instance name, campaign and smart list.
Please open a support case if those details need to be kept private.