Which opera, if any,  Venus and Adonis or Bluebeard's Castle has more acts ?
Bluebeard's Castle Bluebeard's Castle (Hungarian: A kékszakállú herceg vára ; literally: "The Blue-Bearded Duke's Castle") is a one-act opera by Hungarian composer Béla Bartók. The libretto was written by Béla Balázs, a poet and friend of the composer, and is written in Hungarian, based on the French literary tale "La Barbe bleue" by Charles Perrault. The opera lasts only a little over an hour and there are only two singing characters onstage: Bluebeard ("Kékszakállú "), and his new wife Judith ("Judit " ); the two have just eloped and Judith is coming home to Bluebeard's castle for the first time.
William Tell (opera) Guillaume Tell (English: William Tell , Italian: Guglielmo Tell ) is a French opera in four acts by Gioachino Rossini to a libretto by Étienne de Jouy and Hippolyte Bis. Based on Friedrich Schiller's play "William Tell," which drew on the William Tell legend, the opera was Rossini's last, although he lived for nearly forty more years. Fabio Luisi said that Rossini planned for "William Tell" to be his last opera even as he composed it. The overture, in four sections and featuring a depiction of a storm as well as a vivacious finale, the "March of the Swiss Soldiers," is often played.