@natmcd99,
In case of UVs sum of individual line items will always be equal or higher than the total because of deduplication.
Let's say a visitor reached to the site via Paid search first and later reached to your site via Affiliate channel. In this case user is same but used 2 different channel to reach out to your site so individually both the channels will get 1 UV each but in total it will be 1 UV only. So the sum will be 2 and total will be 1.