ruby difference engine

Question

Looking for a Ruby differencing engine. So you can do some of the same things meld viewer does.

For example you have this first set of code per line:

1. String1
2. String2
3. String3

2nd set:

1. String1
2. String3
3. String4

The diff would come out to show lines 2 and 3 are different.

I already am using this one: http://github.com/pvande/differ, but it's definitely not perfect but pretty good. I would like to add on to it, however I'm trying to find some knowledge on another one before going further with this differ.