[Hampshire] File compares

Hi,

I have two large directories that should be the same but might not due
to file system problems.
Does anyone know of a program that can compare two directories and all
sub directories?
I tried sha1sum , but it does not have a recurse option.

Any other tools out there.

Also, I have two other directories, one has changed and the other is a
LVM snapshot from one month ago.
Is there a way to do a compare what the differences at the file level
between an LVM snapshot and the partition it is a snapshot off?
The compare has to be good, so simple file timestamps is not good
enough. the contents of the files have to be checked.

Kind Regards

James