Terminology: Camera Tracking, Camera Relocalization
In the context of SLAM papers, camera tracking means &quot;local relative pose estimation of different views of the scene viewed by a given camera&quot;. It's also called visual odometry. What is important in this task is to get accurate estimates of from-to-frame (or in a small time window) camera displacements. It's to make a difference with mapping where you have global map optimization applied (think loop closures or global bundle adjustment). I refer you to the PTAM paper for more details as to why these 2 tasks are considered.
Relocalization means your robot has a map of a known environment, then you kidnap and blind it, and when you uncover its sensors you want it to recognize what is its new position with respect to the map it already knew (you did not bring it to an unknown place).