Segment vs dimension differences

We have a classification on the tracking code that rolls up to different campaigns. This is not the marketing channel or last touch channel, etc.

Suppose I use the campaign rollup at look at a campaign, email, for example, and I look at entries, orders participation and revenue participation over the past 7 full days.

Then for the same timeframe, I create a segment where the campaign rollup = email and it’s a visit level segment. I also look at entries, orders participation, and revenue participation.

Why would the orders and revenue be different? Both are using participation metrics over the same timeframe. If a visit had an email entry and ordered, it should show in both cases.

We have two reports supplying two different values each week and I’m trying to a) explain where the difference comes from and b) determine which report is showing what we are asking of it.

My theory is the ‘visit’ level segment is pulling in orders where the visitor had an email entry within 30 days and it’s being included.