"I don't think they're alike at all," the comedian (pictured) told Metro recently, adding that I Can't Sing!, which premieres at the Palladium next year, is "a very different show and very funny".
Viva Forever!, which opened in December to decidedly unenthusiastic reviews, is closing at the Piccadilly Theatre at the end of June.
I Can't Sing!, which has music by Steve Brown, is being directed by Olivier Award-winner Sean Foley.
It's produced by Stage Entertainment UK and Syco Entertainment, which is owned by X Factor supremo Simon Cowell, who will reportedly be played by Alexander Hanson in the stage show.
According to recent press material: "In turn irreverent, anarchic and strangely touching I Can't Sing! is an affectionate poke at the world's most talked about talent show that will please friends and foes of The X Factor in equal measure."
Whether it will win the public vote remains to be seen...