Question

Difference between primary and secondary baseline

Answer 1

Project baselines are default baselines which can be used as the initial baselline when you first start to update your project.
This baseline will apear by default in all the other users login also.you should always keep this as your baseline if you have only one baseline to maintain.

On the other hand primary/secondary/tertiary baselines can be considrered as user specific baselines.
these baselines are used where you will have to maintain 2 or more baselines for your comparision and analysis.
these user baselines will not appear in other users login when you are refering to the same project.

Answer 2

secondary is a level after primary ,it includes 1,2,3,4,5 classes where as primay is a level before secondary