How to compare the output of two commands?

[Sonixxfx]

Hi,

I am using two large commands that both output a pretty large amount of text. I want to compare these two lists of text, but I do not want to redirect it to textfiles to be able to do that. I have tried to compare the output with diff, by using some bash functions, but I keep getting errors.
So does someone know of a way to compare the output?

To be more specific I want to compare a list like this, but much longer, to another list of text that has the same structure:

/usr
/usr/share
/usr/share/doc
/usr/share/doc/unzip
/usr/share/doc/unzip/copyright
/usr/share/doc/unzip/BUGS
/usr/share/doc/unzip/ToDo
/usr/share/doc/unzip/changelog.Debian.gz
/usr/share/doc/unzip/History.550.gz
/usr/share/doc/unzip/History.551.gz
/usr/share/doc/unzip/History.552.gz
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/funzip.1.gz
/usr/share/man/man1/unzip.1.gz
/usr/share/man/man1/unzipsfx.1.gz
/usr/share/man/man1/zipgrep.1.gz
/usr/share/man/man1/zipinfo.1.gz
/usr/bin
/usr/bin/unzip
/usr/bin/funzip
/usr/bin/unzipsfx
/usr/bin/zipgrep
/usr/bin/zipinfo

Thanks for your help.

Regards,

Ben