16/04/2012 13:31 BST | Updated 16/04/2012 13:49 BST

'Smash' Star Jack Davenport: 'Glee's A Karaoke Show'....

"We're grateful to Glee, but we're nothing like Glee," says Jack Davenport, star of Steven Spielberg's musical TV showSmash.

The This Life actor plays a British director, Derek Wills, in the US series centering around the staging of a musical about Marilyn Monroe. And Davenport is keen to point out the differences between the hit all-singing all-dancing show Glee and his "adult" drama, Smash, before it airs in the UK this weekend.

"Until Glee came along, musicals and TV were not happy bedfellows, they never really worked. We are very grateful to Glee for creating a gap that we can sneak into, but beyond that there are huge differences.

"Glee's set in a high school, it's a karaoke show, they sing only covers, also people sing just because they're feeling so much that they've just 'got to sing' because they're teenagers," Davenport explains.

He reasons: "In our show people sing because it's a world where people sing for a living. So people only sing because they would do in real life. Plus, we're trying to build a real musical here, so each week there is original music."

In Smash, the Pirates of The Caribbean star Davenport's character is among those tasked with deciding who is best equipped to star as Marilyn in a new Broadway show: Katharine McPhee's Karen - a naive and morally-grounded actress looking for her first big break - or Megan Hilty's seasoned Ivy - who's willing to do almost anything to get the part.

Jack Davenport with Katherine McPhee in Smash - but is she his favourite Marilyn?

Which 'Marilyn' did Davenport take to the most? Well, if he has a favourite, he's not saying...

"They're both, from a technical point of view, qualified to play this part. They both sing like angels. Obviously Megan looks more like Marilyn but if you stick a wig on Kat you'd be amazed, she could get away with it too.

"But the thing that's really fascinating is, there's something essential about them both. What one has, the other one doesn't have so you've got this real creative dilemma - do you go with the veteran or the new girl? One is a bigger risk than the other one."

Smash starts on Sky Atlantic HD from the 21 April. Here are the music-makers in action...