The D3000, the D3100 is built around a 14.2 megapixel CMOS sensor, bringing not only live view but also Full HD video capture to Nikon’s entry-level model.
Compared to the D3000 the body gets a slight refresh, gaining an extra button to the left of the screen, a drive mode switch at the base of the mode dial, a sprung lever to engage live view and a direct record movie button.
The D3100 has a new 11-point AF system, and Nikon has also added an additional AF-F autofocus mode to allow better focusing in live view and autofocus during video shooting.