Bricks
To put this claim to the test, we shot a number of indoor and outdoor photos on both devices to see the difference for ourselves.
In this first example, you'll see a photo of bricks taken with the iPad (left) and the iPhone 4S (right). Can you spot any differences in detail, color or clarity? Neither could we.
Admiral Sackbar & friend
The iPad photo is on the top, with the iPhone version is below it. You'll notice that the iPhone photo is slightly closer, and tricks the camera into a shallower focus. This was an unintentional, but recurring quirk, caused by how we naturally wanted to hold each device and view its screen.
Sky
Side-by-side shots of telephone lines against blue skies, with the iPad again on the left, and the iPhone 4S on the right. The blue of the iPhone photo looks slightly more saturated, but otherwise the photos handle details and color gradients similarly.
Flower focus
Here we have a close-up of some flowers with the ipad on the left and the iPhone 4S shot on the right. In both cases, the tap-to-focus feature brought the foreground flowers into a shallow focus. If there's a reason the iPad photo looks a little sharper, I'd credit the fact that the large screen made it much easier to identify that the shot was in focus and framed well.
Indoor portrait
CNET's Dong Ngo poses for a portrait in the windowless subterranean dungeon known as CNET Labs. Again, we have the iPad photo on the top and the iPhone 4S photo below it. In both instances the built-in face detection and autofocus worked as advertised.
Old Cadillac
This photo of an old Cadillac demonstrates how identical the iPad's camera (top) and iPhone 4S (bottom) really are under some conditions.
Peeling paint
Here's another shot where we are stumped to tell the difference between the iPad's camera (top) and the iPhone 4S (below).
Hydrant
This hydrant offered an odd mixture of hues and textures to test the cameras against. But aside from the iPhone 4S (below) offering a slightly color richer saturation than the iPad (top), both cameras handled the photo identically when it came to focus and details.
In the garden
A close, but not too close, shot of some flowers. I'll let you decide which one's the iPad and which is the iPhone 4S.