As far as I recall, every version update (except minor bug fixes like from 2.5.4 to 2.5.4.1) has involved some database structure changes. There is no official way to roll back from a later version to an earlier one.
Whether this can be achieved in an emergency by hacking the database directly - you would need guidance from the Mendix guys to even attempt this. Better do your testing thoroughly in the T-env before pushing to P-env to avoid this issue
There will probably be some changes. And running a previous version of the framework on a later version of the database isn't officially supported. Personally I'd just record the changes it makes and try to reverse them in case you want to rollback for some reason.