Épuiser vs. fatiguer

The French verbs 'épuiser' and 'fatiguer' both relate to making someone tired, but they have subtle differences in intensity and usage.

Épuiser

'Épuiser' means to exhaust completely, to drain all energy or resources. It implies a more intense and thorough state of tiredness.
Le marathon a épuisé les coureurs.
(The marathon exhausted the runners.)
Ce projet a épuisé toutes nos ressources financières.
(This project has exhausted all our financial resources.)
La canicule m'a complètement épuisé.
(The heatwave has completely exhausted me.)

Fatiguer

'Fatiguer' means to tire out or make weary. It suggests a more general state of tiredness that may not be as severe as 'épuiser'.
Le long trajet en voiture a fatigué les enfants.
(The long car journey tired out the children.)
Ce travail me fatigue beaucoup.
(This work tires me out a lot.)
Les exercices de mathématiques ont fatigué les élèves.
(The math exercises tired the students.)

Summary

While both 'épuiser' and 'fatiguer' relate to causing tiredness, 'épuiser' implies a more severe, complete exhaustion of energy or resources, whereas 'fatiguer' indicates a more general state of being tired or worn out. 'Épuiser' is often used in more extreme situations, while 'fatiguer' is more common in everyday contexts.