Before we start any AEM upgrades we should ensure that a detailed study is done on the release notes.
If the upgrades are planned to the next direct version (Say AEM 6.4 to AEM 6.5), We can just read the release notes of AEM 6.5 and proceed for the upgrade. But if the case is different (AEM 6.3 to AEM 6.5) ensure we are comparing the release notes for each versions.
In addition to it, since AEM 6.4 onwards, Repository Restructuring occurred.
The following doc may be helpful in finding the correct locations/paths of nodes in AEM 6.5: