$body1="This is the text in the article that is pending.";
$body2="This is the pending text in the article, that is.";
I think you have to be clear between wanting:
a) a 100% match, because all the words are the same, albeit in a different order
b) a straight "diff" operation which tells you char for char which ones need to be altered for body1 to match body2 -- probably only a 30% match -- which is what levenshtein() seems to do.
If it is a) you want then it appears to involve splitting up the string to words?
Something must already exist to do this, it sounds as if it would be useful in many scenarios.
(I'm no greater expert on this than I was in the post you referred to)