[Galaxy Note 10.1 (2014 Edition) Q&A, Help & Troubl] BarryH_GEG:
The N10.1-14 has a PenTile RGBW display which means the PPI count is 299 but there are fewer RGB pixels to accommodate the addition of the white pixel. The white pixel reduces the number of RGB pixels by 8% each. Even with that, the N10.1-14 has more RGB pixels per inch (274) than the iPad Air's 264 so from a sharpness perspective the N10.1-14's superior.

From WiKi....

PenTile RGBW technology, used in LCD, adds an extra subpixel to the traditional red, green and blue subpixels that is a clear area without color filtering material and with the only purpose of letting backlight come through,[11] hence W for white. This makes it possible to produce a brighter image compared to an RGB-matrix while using the same amount of power, or produce an equally bright image while using less power.

The PenTile RGBW layout uses each red, green, blue and white subpixel to present high-resolution luminance information to the human eyes' red-sensing and green-sensing cone cells, while using the combined effect of all the color subpixels to present lower-resolution chroma (color) information to all three cone cell types. Combined, this optimizes the match of display technology to the biological mechanisms of human vision. The layout uses one third fewer subpixels for the same resolution as the RGB stripe (RGB-RGB) layout, in spite of having four color primaries instead of the conventional three, using subpixel rendering combined with metamer rendering. Metamer rendering optimizes the energy distribution between the white subpixel and the combined red, green, and blue subpixels: W <> RGB, to improve image sharpness.

The display driver chip has an RGB to RGBW color vector space converter and gamut mapping algorithm, followed by metamer and subpixel rendering algorithms. In order to maintain saturated color quality, to avoid simultaneous contrast error between saturated colors and peak white brightness, while simultaneously reducing backlight power requirements, the display backlight brightness is under control of the PenTile driver engine. When the image is mostly desaturated colors, those near white or grey, the backlight brightness is significantly reduced, often to less than 50% peak, while the LCD levels are increased to compensate. When the image has very bright saturated colors, the backlight brightness is maintained at higher levels. The PenTile RGBW also has an optional high brightness mode that doubles the brightness of the desaturated color image areas, such as black&white text, for improved outdoor view-ability.​

Some folks have noticed some funkiness between certain colors at full saturation due to conflicts between the sub-pixels when all are called to be active under certain display conditions. Yellows and greens on a white background have been pointed out. So depending on what's displayed those with keen eyes could detect some differences between the iPad Air's true RGB stripe display and the N10.1-14's RGBW display.

However, for the same resolution and size the PenTile screen can appear grainy, pixelated, speckled, with blurred text on some saturated colors and backgrounds when compared to RGB stripe color. This effect is understood to be caused by the restriction of the number of subpixels that may participate in the image reconstruction when the color is fully saturated. In the RGBW case, this is caused as the W subpixel will not be available in order to maintain the saturated color. For all other cases, text and especially full color images are fully reconstructed.
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