Hello,

indeed, the difference is small between the two concepts.

In addition, it is possible to receive a ticket that will be a change request (you can then copy the ticket into a change request)
On tickets, we will record incidents (bugs, request for assistance, non-compliance ...) and above all, we will be able to track the time spent on these tasks which cannot be scheduled.
With the change request, we are between the ticket and the requirement. You can describe these requests in detail and you can estimate the cost the the change.

Hoping to have answered at least your question,
regards