Matrimonio vs. nozze

The Italian words 'matrimonio' and 'nozze' both refer to a wedding, but they have subtle differences in usage and connotation.

Matrimonio

'Matrimonio' refers to the institution of marriage or the wedding ceremony itself. It is often used in more formal or legal contexts.
Il matrimonio si terrà in chiesa.
(The wedding will be held in church.)
Hanno celebrato il loro matrimonio l'anno scorso.
(They celebrated their wedding last year.)
Il certificato di matrimonio è un documento importante.
(The marriage certificate is an important document.)

Nozze

'Nozze' typically refers to the wedding celebration or festivities. It often implies a more joyous and social aspect of the wedding.
Siamo stati invitati alle nozze di Maria e Giovanni.
(We were invited to Maria and Giovanni's wedding celebration.)
Le nozze d'oro si festeggiano dopo 50 anni di matrimonio.
(The golden wedding anniversary is celebrated after 50 years of marriage.)
La festa di nozze è stata meravigliosa.
(The wedding party was wonderful.)

Summary

While 'matrimonio' focuses on the formal and legal aspects of a wedding, 'nozze' emphasizes the celebratory and festive elements. 'Matrimonio' is more commonly used for the ceremony and official matters, while 'nozze' is often used when referring to the joyous occasion and related festivities.