The 25-year-old, who rose to prominence at the same time as her fellow pop singers, said she did not like sticking to formula music and would rather prefer to take a different road.
'I kind of always knew we would all differentiate ourselves from one another,' Contactmusic quoted her as telling MTV News.
'Musically, they've stuck to a formula that works for them and, obviously, has always proven successful. I don't think I found that same success singing music that really, at the end of the day, I wasn't happy singing,' she added.
Mandy further defended her new album 'Amanda Leigh' based on '70s sort of California pop', insisting: 'It wasn't a bold gesture to try and show that I was an adult. I sort of have taken my baby steps to get to where I am today. I feel comfortable singing the music that I'm singing, because it's coming from me, finally.'