Photoshop VS Illustrator

Which is better? Photoshop or Illustrator?

The Answer: They're both "better"

:: Adobe Photoshop ::

Photoshop is a 'bitmap' image processing and manipulation program. It's ideally suited for creating, modifying and outputting digital images of a photographic nature, which share a common fundamental structure: pixels in a bitmap. Simplified, but primary operations would be:

• Access/acquisition of digital graphics photographic in nature 
• Add, subtract, modify, colorize, pixels in the images 
• Produce digital files where the whole image is part of a 'fixed' pixel structure (the 'bitmap') 
• Prepare complicated color/BW images for further processing in page layout programs for high resolution printing

:: Adobe Illustrator ::

Illustrator is a vector-based postscript drawing program. It functions by generating curved paths (Bezier curves) connected by modifiable anchor points. These anchors, with their handles are ultimately editable, and never 'leave' the structure of the file.
  

A vector based drawing program creates the various elements of the image as individual vector objects which retain their characteristics and do not become part of a 'bitmap'.