CQL search does not return all results as shown in confluence advanced search

[yboodhan]

I used confluence advanced search (Click search bar > Confluence advanced search > Selected type and contributor) to search for all pages created by a contributor. I see results saying "Showing 25 of 45 results".

The url for this search was: https://{domain}.atlassian.net/wiki/search?type=page&contributors={useraccountid} where {domain} and {useraccountid} were populated.

I created the equivalent CQL: 

contributor="useraccountid" and type="page"

However, when calling the API, I only get 37 results back, not the 45 results I expected. 

Are there any assumptions made when using CQL search that eliminate certain content from being returned?

What could explain the mismatch of content count I see returned on the advanced search feature in the ui and the API results using the above query?