Hi Roisin,
I asked the team about your issue, and here's what they said...
Conversations can continue after a report is run so there is a chance data will change, especially if you are looking at real-time or today's data. Both the report and the export run the same exact query though, so if you run at the same time, the data should be the same.
If you think there's an issue, we recommend that you create a customer care case so we can further investigate, but they are both running the same code.
Here's a link to our PureCloud Customer Care info, in case you choose that path.
https://help.mypurecloud.com/articles/contact-purecloud-care/
I hope this helps.
Thank you,
Clay