Why is there a difference between the number of visits on ThankYou Analytics and my web analytics solution?
Data discrepancies: Understanding the causes of divergence
We exclude from traffic user agents considered to be non-human (bots, tools, etc.), payment URLs, pre-production URLs and test URLs. Depending on what is excluded from the traffic in your web analytics solution, this may explain the difference.
This difference may also be explained by the difference of definition between the two platforms: session duration or session duration, in addition to the campaign.