Creating new Object in yii

I’ve been a java developer,and now want to do something in Yii, so anyone please can tell me what’s difference between using brackets in creating new object in yii ,(in Java U have to use brackets)

for example:

$model=new AboutUs;


$model=new AboutUs();

no difference, 2 chars less to write.

Even tho its a little obvious, its better to say. If you will pass parameters to the class constructor, you must use brackets.

just to be clear, this is about php, yii has nothing to do with it

Thanks so much Gustavo.