Sujet vs. thème

In French, 'sujet' and 'thème' can both refer to the general idea or topic of discussion, writing, or study. While they are sometimes used interchangeably, there are nuances that distinguish them based on context and usage.

Sujet

The word 'sujet' generally refers to the subject matter or topic of an intellectual work or discussion, often emphasizing the specific focus or issue at hand.
Le sujet de sa thèse est la biologie marine.
(The subject of her thesis is marine biology.)
Nous devons trouver un bon sujet pour notre prochain débat.
(We need to find a good topic for our next debate.)
Le film traite d'un sujet très controversé.
(The film deals with a very controversial subject.)

Thème

'Thème' generally refers to a broader theme or motif that is more abstract; it's often used in artistic contexts to denote a recurring idea or underlying message.
L'amour est un thème récurrent dans ses romans.
(Love is a recurring theme in his novels.)
Le thème de l'exposition est 'La Renaissance en Europe'.
(The theme of the exhibition is 'The Renaissance in Europe'.)
Le compositeur a choisi le voyage comme thème central de sa symphonie.
(The composer has chosen travel as the central theme of his symphony.)

Summary

'Sujet' tends to emphasize a more specific and immediate topic or issue that is the focus of attention, while 'thème' often conveys a wider, more abstract concept or underlying idea that recurs across a work or series of works.