A Life for the Tsar is a  Russian libretto with four acts, Tosca an Italian libretto has how many acts?
A Life for the Tsar A Life for the Tsar (Russian: Жизнь за царя , "Zhizn' za tsarya"), as it is known in English, although in Soviet times its name was "Ivan Susanin" (Russian: Иван Сусанин ) is a "patriotic-heroic tragic opera" in four acts with an epilogue by Mikhail Glinka. The original Russian libretto, based on historical events, was written by Nestor Kukolnik, Egor Fyodorovich (von) Rozen, Vladimir Sollogub and Vasily Zhukovsky. It premiered on 27 November 1836 OS (9 December NS) at the Bolshoi Kamenny Theatre in St. Petersburg. The historical basis of the plot involves Ivan Susanin, a patriotic hero of the early 17th century who gave his life in the expulsion of the invading Polish army for the newly elected Tsar Mikhail, the first of the Romanov dynasty, elected in 1613.
Aida Aida (] ) is an opera in four acts by Giuseppe Verdi to an Italian libretto by Antonio Ghislanzoni. Set in Egypt, it was commissioned by and first performed at Cairo's Khedivial Opera House on 24 December 1871; Giovanni Bottesini conducted after Verdi himself withdrew. Today the work holds a central place in the operatic canon, receiving performances every year around the world; at New York's Metropolitan Opera alone, "Aida" has been sung more than 1,100 times since 1886. Ghislanzoni's scheme follows a scenario often attributed to the French Egyptologist Auguste Mariette, but Verdi biographer Mary Jane Phillips-Matz argues that the source is actually Temistocle Solera.