Reflet vs. réflexion

The French words 'reflet' and 'réflexion' both relate to the concept of reflection, but they have distinct usages and nuances in the French language.

Reflet

'Reflet' refers to the image or light that is reflected from a surface, typically in a visual or physical sense.
Le reflet de la lune brille sur l'eau calme du lac.
(The reflection of the moon shines on the calm water of the lake.)
Elle admirait son reflet dans le miroir.
(She admired her reflection in the mirror.)
Les reflets dorés du soleil couchant illuminaient la pièce.
(The golden reflections of the setting sun illuminated the room.)

Réflexion

'Réflexion' can refer to both the physical process of light being reflected and, more commonly, to the act of thinking deeply or contemplating.
La réflexion de la lumière sur l'eau crée des motifs fascinants.
(The reflection of light on water creates fascinating patterns.)
Après mûre réflexion, elle a décidé de changer de carrière.
(After careful reflection, she decided to change careers.)
Cette question mérite une réflexion approfondie.
(This question deserves deep reflection.)

Summary

While 'reflet' is primarily used for visual reflections and images, 'réflexion' has a broader usage, encompassing both physical reflection of light and mental contemplation. 'Reflet' is more concrete and observable, whereas 'réflexion' often implies a more abstract or intellectual process.