Fatigue is Hit Points and is equal to Endurance. Character Pool is experience points. Character Pool points may also be spent in downtime to increase skills. In order to learn a Novice skill, character points must be spent on a chance on a d10 to learn a skill. It is an interesting mechanic, but I have no idea what it is attempting to represent.
Stress is fatigue for psychics.
A character may also elect to incur stress in order to improve a success level. What Sanity is to Call of C thulhu , Stress is for The 23rd Letter . At low levels, Stress can cause headaches or dizziness. At higher levels, Stress can cause hallucinations, eating disorders, mental illness, and heart strain. The kicker is that Stress can only be reduced through therapy, drugs, and rest, and rest means a day with eight hours sleep and no activity.