A point is a typographic meassuremeasure, that means it is a physical meassuremeasure of length, like miles, inches, meters or an astronomical unit. Historically, the length of a point varied from different locales and cultures, but with the rise of desktop publishing and internationalisation the following convention has established:
In the late 1980s to the 1990s, the traditional point was supplanted by the desktop publishing point (also called the PostScript point), which was defined as 72 points to the inch (1 point = 1⁄72 inches = 25.4⁄72 mm = 0.3527 mm).
A pixel is the smallest unit of digital image data. That is the same to say a pixel is without actual physical size. Pixels are used to display an image on screen or print it, converting the image information in pixels to physical representation. Screens have their pixel density measured in ppi (pixels per inch), whereas printed images are measured by dpi (dots per inch) - for both the same amount of image pixels may result in hugely variable physical sizes, e.g., a 100X100100 X 100 pixel image will be huge displayed on a outdoor advertising screen, or tiny when printed on paper at 300 dpi.
