Next Nexus has a "Large Camera"?

So this is a question based off of the image:


So folks saw that camera opening and said it was large. Now my question is (and its probably simple):

I don't see how the iris is any bigger than the N4. All that's different is the area around the camera lens opening. So what does this mean actually? Like am I totally off base - or is the design made to make the viewer think its better than it really is?

Does that serve any particular purpose?