Explaining it further
Assume i have two strings like below
I am a super boy who can Fly! Really .
I am super boy who can Break walls!
Really .
So some characters are similar I am super boy who can and Really . .
Is there anything ready to use to find percentage similarity/diffrence between those two strings.
You should look into Levenshtein Distance.
http://en.wikipedia.org/wiki/Levenshtein_distance