Which opera, if any,  Venus and Adonis or Bluebeard's Castle has more acts ?
Venus and Adonis (opera) Venus and Adonis is an opera in three acts and a prologue by the English Baroque composer John Blow, composed in about 1683. It was written for the court of King Charles II at either London or Windsor. It is considered by some to be either a semi-opera or a masque, but "The New Grove" names it as the earliest known English opera.
Erwin und Elmire Erwin und Elmire is an opera in two acts by Duchess Anna Amalia of Brunswick-Wolfenbüttel, with a libretto by Johann Wolfgang von Goethe, after Oliver Goldsmith's ballad of Angelica and Edwin, "The Hermit", in his sentimental novel "The Vicar of Wakefield".