The P7700 has a more pronounced grip than the P7100's, with a more appropriate, traditional placement of the subcommand dial.
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Top
The top control layout remains the same as on the P7100, although the absence of the viewfinder removes the need for a higher shoulder on the flash side of the camera.
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Back
With the exception of the missing optical viewfinder, the control layout on the back is more or less the same as on the P7100; the thumb rest has shrunk, and the flash pop-up control is different.
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Display
Nikon swaps the tilting LCD for a flip-out-and-twist articulated version