Solved
Final entity on which to place bids (Search)
For Search, are you setting bids for every unique keyword and match-type combination?
The final entity on which we place bids is called a Bid Unit.
A Bid Unit (in Search) includes the keyword and match type. In addition to that, we have also included campaign level information. So the same keyword and match type combination, if they are in different campaigns, will get different bids.
So in short, a Bid Unit = a combination of keyword + match type + campaign.