What is the difference between Ultra pixel and Mega Pixel camara? How we can compare Ultra Pixel and Mega pixel? And what is the difference between these two camara technologies.
Extracted from UltraPixel vs Megapixel: HTC One &amp; iPhone 5 Camera Shoot-Out:
Ultra-Pixels:

Basically the sensor on the HTC One features larger pixels for better low light sensitivity and, on paper, better overall camera performance.
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We have to understand that “ultrapixel” is just HTC’s marketing team saying that the pixels on the HTC One’s sensor are larger. Here’s how it works: the sensor on the HTC One isn’t larger than the sensors on other modern phones: 1/3.2-inch is what HTC used in the One and the same size is also present on the iPhone 5, Galaxy S III, or Lumia 920. A larger sensor means having something like the Nokia 808 PureView has with its 1/1.2 inch sensor.

Some other site described that term as &quot;plain market buzz&quot;. More on the term UltraPixel can also be found at Wikipedia.
Megapixel, on the other hand, is a measurement term, describing the resolution of an image – a term used not only for the number of pixels in an image, but also to express the number of image sensor elements of digital cameras or the number of display elements of digital displays.