Long time I was searching for an application which does what you can read in the title of this posting.
I was working with Mac OS X panther, so it was even more difficult to find an app, because of an old OS and a G4 Prozessor.
Now with my new Mac I can use and test the recent apps for my needs. In the windows and linux world are the following apps very popular:
- beyond compare | comm. | win
- meld | free | linux
For Mac OS X however it’s hard to find such popular and worth proved tools. These days I found a saving blog post from echeng and many useful comments for my problem.
For a better overview I made a list of the mentioned code/folder compare, sync, diff and merge applications:
- zsCompare | comm. | mac os x
- ChronoSync | comm. | mac os x
- SmartSynchroniz | comm. | windows, linux, mac os x
- Araxis Merge | comm. | windows, mac os x
- Match | comm. | windows, linux
- DeltaWalker | comm. | windwos, linux, mac os x
- diffmerge | free | windows, linux, mac os x
- Guiffy | comm. | windows, linux, mac os x
- changesapp | comm. | mac os x leo
My decision flew to diffmerge because it’s free and does what I want – albeit not very intuitive but it does – namely show me the differences between folders and the exact differernces in the file contents.
When I have the time I’ll enhance more information. You’re invited to help me 
Thx to echeng and the commentators.