As both formats are very similiar ( due to the same concept), there is also one significant similiarity.

The most winenrs of both shows have been just so called “one-hit-wonders”. That means that no-one of them has been really succesful for more than one or two singles.

These are the winners of the American Idol since 2002

 

* 2002: Kelly Clarkson
* 2003: Ruben Studdard
* 2004: Fantasia Barrino
* 2005: Carrie Underwood
* 2006: Taylor Hicks
* 2007: Jordin Sparks

 

The Winners of german Deutschland sucht den Superstar - DSDS - are as below:

 

2003: Alexander Klaws

2004: Elli Erl

2006: Tobias Regner

2007: Mark Medlock

 

I think the only real superstar is Kelly Clarkson, who became an international Superstar. I imagine noone of the german winners of DSDS is well known outside Germany.