I came across this program WinMerge that is usefull for comparing the content of text files.
Now when I'm writing scripts I sometimes end up with multiple copies of scripts as I work at home and do some updates at work in my free time.
Or sometimes its several weeks later when I get back to scripting if i'm busy and I'm not sure where I left off, or which copy was the best working copy.
This program will display both copies beside each other and highlights in yellow the differences or changes between the scripts.
Its a nice easy program and best of all...Its free!
http://winmerge.org/