Words vs. WORDS

Words and WORDS are two very similar types of text objects. A word
is a string of "word" characters, which include letters, numbers,
and underscores. A WORD, on the other hand, is any string of
non-whitespace characters.

In the example below, the words are underlined by 'w', and the
WORDS are underlined by 'W'.

    This "stuff" is not-so difficult!
    ---------------------------------
    wwww  wwwww  ww www ww wwwwwwwww
    WWWW WWWWWWW WW WWWWWW WWWWWWWWWW

As is visible in the example, the words do not include any of the
non-alphanumeric punctuation, while the WORDS do include the
quotes, hyphen, and exclamation point. Also notice that 'not-so'
contains two words, but only one WORD.