import re
s = raw_input('Type a word: ')
slower=''.join(re.findall(r'[a-z]',s))
supper=''.join(re.findall(r'[A-Z]',s))
print slower, supper
Prints:
Type a word: A Title of a Book
itleofaook ATB
Or you can use a list comprehension / generator expression:
slower=''.join(c for c in s if c.islower())
supper=''.join(c for c in s if c.isupper())
print slower, supper
Prints:
Type a word: A Title of a Book
itleofaook ATB