During his time in charge of the Premier League champions, reports emerged claiming that Mancini did not have the strongest of relationships with his players.
In an interview with the Manchester Evening News, Chapman said: "How do Mancini and Pellegrini differ? Well, [Pellegrini] actually speaks, which is more than the previous one did.
"He is a cool guy, a gentleman and says hello. It's certainly a lot happier dressing room."
Pellegrini guided City to Capital One Cup glory and the league title in his first season in charge.