The difference between using ',' and 'as' in except statements, is as follows:
Both ',' and 'as' are same functionality wise; but their use depends on the python versions as follows.
In Python 2.5 and earlier versions, use of the 'comma' is recommended since 'as' isn't supported.
In Python 2.6+ versions, both 'comma' and 'as' can be used. But from Python 3.x, 'as' is required to assign an exception to a variable.
As of Python 2.6 using 'as' allows us an elegant way to catch multiple exceptions in a single except block as shown below
except (Exception1, Exception2) as err
is any day better than
except (Exception1, Exception2), err