is one thing
Digo que la fábrica del alcalde Antonio Moraes es una cosa, y su perra otra.
I say that Mayor Antonio Moraes' factory is one thing, and his dog is another.
— El Auto De La Compadecida (2000)
Enamorarse es una cosa, casarse es otra.
Falling in love is one thing, getting married is another.
Life is a funny thing.
Es una cosa seria, acá lo llamamos Platón porque vive de la Academia.
It's a serious matter; here we call him Plato because he lives off the Academy.
— El secreto de sus ojos (2009)