format sring question

[Lowell Kirsh]

In Peter Norvig's Infrequently Answered Questions he explains that the 
following 2 fnctions look almost identical but are not the same:

def printf(format, *args): print format % args,

def printf(format, *args): print str(format) % args,

The only difference is that in the second one, str(format) replaces 
format. If args are not given and the format string contains a '%', the 
first will work but the second will not. Why is this so? It seems to me 
like '100%' and str('100%) are the same object, no?

Lowell