Comparing 2 strings.

I currently store text from a MySQL blob field in a string $orig_text. I need to compare that with something someone type in from a form stored in $new_text. How would I go about comparing them to see if they are different or exactly the same? strcmp doesn't look like it will handle this too well. I can't go by the number of characters in the string either. Someone may be able to use new words but keep the length of the string the same. Thanks, Ed