Thank you very much, Martijn and ThompsonPaul, for your responses. I searched everywhere for an answer online, but couldn't find an answer to this somewhat obscure question. Your answers finally clarify this for me. Thanks again!

I have two sites: a blog and an ecommerce site. The blog funnels people to the ecommerce site. In Analytics I'm seeing declines in referral traffic from the blog to the ecommerce site. During the same time I'm seeing an increase in campaign traffic to the ecommerce site, with most campaign traffic coming from the blog. I believe the increase in campaign traffic is largely a result of simply having installed more tracking links. This leads me to believe that the declines I'm seeing in referral traffic is simply a result of the increase in campaign traffic. In other words, what was once counted and reported as being referral traffic is now being counted and reported as campaign traffic. So my question is this: In Google Analytics is campaign traffic ALSO reported as referral traffic, or is campaign traffic reported separately and not duplicated in referral traffic reports?

I'll provide a concrete example to make this more clear in case it isn't:

Say site X sends 1000 visits each month to site Y. Say 50 of those visits come from a single link on X. If that link is changed so that campaign Z data info added (via the Google URL Builder), would you expect to then see 950 referral visits each month from site X to site Y plus 50 campaign visits to site Y via new campaign Z, or would you continue to see 1000 referral visits plus the new 50 campaign visits?

Many thanks in advance to anyone that can shed some light on this.