How do Python 2 and Python 3 versions differ in functionality and syntax?

Main differences between Python 2 and Python 3:

• Print syntax:

  • Python 2: print "Hello" (statement)
  • Python 3: print("Hello") (function)

• Integer division:

  • Python 2: 5 / 2 returns 2 (integer division)
  • Python 3: 5 / 2 returns 2.5 (float division), for integer division use 5 // 2

• Unicode:

  • Python 2: strings are byte sequences by default, use u"string" for Unicode
  • Python 3: strings are Unicode by default

• Iterators:

  • In Python 3, many functions like range(), map(), filter() return iterators instead of lists, saving memory.

• Exception handling:

  • Python 2: except Exception, e:
  • Python 3: except Exception as e:

Python 3 is the modern version with improvements and fixes, and it is recommended to use it for new projects.