How come I experience a discrepancy between reported clicks for an Cxense Display campaign and the Google Analytics reported referrals for that specific landing page?
First of all, Cxense Display reports clicks or unique clicks while Google Analytics reports visits on referral level. That's like comparing apples with oranges.
Secondly, there are a lot of technical obstacles between the Ad Servers click and Google Analytics registering a correct referral source.
“When an ad server delivers line items that are hosted by a third party, reporting discrepancies between the two systems occur, and it is common to see campaign variances of up to 20%.”
“Comparing Apples to Oranges – Clicks vs. Visits”