Does unicode() equal to unicode(sys.getfilesystemencoding()) ?

[人言落日是天涯，望极天涯不见家]

The follow statement comes from the Python 2.5 documentation
--------------
encode( [encoding[,errors]])

Return an encoded version of the string. Default encoding is the
current default string encoding. errors may be given to set a
different error handling scheme.
---------------
what's the "Default encoding" mean ? Does it equal to the
sys.getfilesystemencoding()?
If yes, but :

>>>unicode('中国', sys.getfilesystemencoding())
u'\u4e2d\u56fd'
>>>unicode('中国')
Traceback (most recent call last):
  File "<input>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd6 in position
0: ordinal not in range(128)

It seems the "Default encoding" is not equal to the
sys.getfilesystemencoding(). And then,  what is it ?