Diffrence between two dirs?

diff -qr dir1 dir2 | sort

That will compare files in two directories.

If you're a sadist you can drop the q argument (and the | sort pipe) and you'll see all the differences between all the files... But the output is pretty hard to interpret like that.

If you do have a lot to handle, perhaps piping through less (just add | less to the command) will let you view it a little easier.

meld is a good graphical diff frontend that will show you a side-by side listing of files. Install meld with Ubuntu Software Center:

Or use these commands with the terminal:

sudo apt-get install meld
meld dir1 dir2

As to GUI, kdiff3 seems to be able to compare directories.