I'm afraid, it is not possible to view changes specifically made from the AdWords UI and the API, using the AdWords API. The
CustomerSyncService can be used to retrieve the changed entities for a customer account or a campaign based on the given date range
as long as it is within the last 90 days. We currently do not have a
report type that downloads the change history data. However, you could perform the
CustomerSyncService.get() which returns all the changed entities in a customer account and this does not categorize between the UI and API separately. This said, I will share your interest with the rest of the team. Please keep an eye out on our
blog for any new announcements.