S'appeler vs. se nommer

In French, 's'appeler' and 'se nommer' are both verbs related to naming and are often used interchangeably. However, they can have different connotations and are used in slightly different contexts.

S'appeler

Used more frequently in everyday conversation, it translates literally to 'to call oneself'. It is commonly used when someone is giving their name or asking for someone else's name.
Je m'appelle Marie.
(My name is Marie.)
Comment tu t'appelles ?
(What's your name?)
Il s'appelle Paul.
(His name is Paul.)

Se nommer

'Se nommer' is used as well but tends to be more formal or literary. It also means 'to call oneself', but it implies a sense of bearing a title or designation, often associated with institutions, places, or literature.
L'association se nomme 'Les Amis de la Terre'.
(The association is called 'Friends of the Earth'.)
Dans le roman, le héros se nomme Alexandre.
(In the novel, the hero is named Alexander.)
Cet endroit se nomme 'La Vallée des Rois'.
(This place is named 'The Valley of the Kings.)

Summary

'S'appeler' and 'se nommer' both express the concept of having a name or being called something in French. While 's'appeller' is more commonly used in casual conversation to ask or give someone's name, 'se nommer' often relates to formal identifications and titles for people, organizations, or places.