What is the difference between Matinee and Opera Pearls?

Aloha.  Since the death of Her Royal Highness, Queen Elizabeth II, there has been a renewed interest in Pearls.  Amongst the die-hard "Classicist" Pearls always have a place in any collection of fine jewelry, but seeing so many pictures of The Queen adorned often in Pearls has created wider interest.
​
Your question would actually be, "What is the difference between Matinee Length and Opera Length Pearls."  It is not so much that one length of Pearls is worn to Matinees and others to the Opera, but rather these terms describe the length of the strand - whenever and wherever worn.

According to the American Gem Society (AGS), Pearls Strands are classified  according to length:

• A collar fits directly against the throat
• A choker rests at the base of the neck
• The princess length reaches near the collarbone
• A matinee length is usually 20-24 inches
• The Opera length is 30-36 inches
• The longest length, known as a rope, refers to all strands longer than 36 inches

Necklaces can also be classified as uniform (where all pearls are about the same size) or graduated (pearls change uniformly from ends to center).

Hope this helps.