Mort vs. décès

In French, the words 'mort' and 'décès' both refer to the concept of death, but they are used in slightly different contexts and carry distinct nuances.

Mort

'Mort' refers to the state of being dead or the concept of death in a broad, general sense. It can be used to describe the death of a person, animal, or even the end of something non-literal, like a feeling or era.
Elle pleure la mort de son chat.
(She is mourning the death of her cat.)
La mort de l'empire a marqué l'histoire.
(The death of the empire marked history.)
La mort lui semble moins effrayante maintenant.
(Death seems less frightening to him now.)

Décès

'Décès' specifically refers to the act of dying or passing away and is most often used in formal or administrative contexts. It implies the process or event leading to death rather than the state of being dead.
Le certificat de décès a été signé par le médecin.
(The death certificate was signed by the doctor.)
Le nombre de décès dus à la maladie continue d'augmenter.
(The number of deaths due to the disease continues to rise.)
Ils ont annoncé le décès de leur président.
(They announced the death of their president.)

Summary

'Mort' and 'décès' both refer to death, but are used differently in French. 'Mort' describes the state of being dead or the broad concept of death, which is suitable for more general contexts. In contrast, 'décès' refers to the act or event of dying and is often used in formal, legal or statistical contexts.