Compare The Barber of Seville opera with the Rigoletto opera.

The Barber of Seville is an 1816 comic opera in two acts by Rossini.  Rigoletto is an 1851 tragic opera in three acts by Verdi.  The works share few similarities other than plot points involving concealed identities and a young woman who functions as an object of desire. 
The Barber of Seville is a lighthearted story of a love triangle among a young woman, a count, and her guardian, who both wish to marry her.  The barber is the confidante to both men and assists in the count's rather convoluted and comical plan to win her away from her guardian by assuming two alternate identities.  In the end, the count and the young woman marry, saving her from a loveless marriage to her guardian.
Rigoletto is the story of a court jester in service to a libidinous duke; Rigoletto the jester has a beautiful daughter whom he has kept sequestered.  Rigoletto unwittingly participates in her abduction, and the daughter unwittingly falls for the duke, believing him to be a poor student. When an assassin comes to kill the duke, the daughter is dressed as a man and allows herself to be killed to spare the duke. Her father, Rigoletto, is shattered.