Gros titre vs. manchette
In French journalism, 'gros titre' and 'manchette' both refer to elements designed to capture the reader's attention, but they are used in slightly different contexts within a newspaper.
Gros titre
'Gros titre' refers to the main headline of a newspaper article, which is typically bold and large to quickly draw attention. It summarizes the most significant point or event covered by the article.
Le gros titre de la journée traitait de l'élection présidentielle.
(The day's headline dealt with the presidential election.)
Les gros titres proclamaient la victoire de l'équipe nationale.
(The headlines proclaimed the national team's victory.)
En gros titres, le journal annonçait un changement politique majeur.
(In big headlines, the newspaper announced a major political change.)
Manchette
'Manchette', while also often a headlining element, denotes specifically the banner headline that stretches across the top front page of a newspaper. It may be composed of one or a few words that are meant to entice readers into buying or reading more.
La manchette 'Victoire Historique!' dominait la une.
('Historic Victory!' dominated the front page.)
L'édition spéciale du journal avait pour manchette 'Choc Mondial'.
(The special edition of the newspaper had 'Global Shock' as its banner headline.)
La manchette évoquait un scandale en gros caractères : 'Révélation Choc!'
(The banner headline hinted at a scandal in large letters: 'Shocking Revelation!')
Summary
'Gros titre' and 'manchette' both play key roles in highlighting important news items in French newspapers; however, 'gros titre' serves as a general term for main headlines, while 'manchette' is specific to front-page banner headlines.