Combining the responses so far, the following bash function will compare the file listings from the zip files. The listings include verbose output (unzip -v), so checksums can be compared. Output is sorted by filename (sort -k8) to allow side by side comparison and the diff output expanded (W200) so the filenames are visible int he side by side view.

function zipdiff() { diff -W200 -y <(unzip -vql "$1" | sort -k8) <(unzip -vql "$2" | sort -k8); }

This can be added to your ~/.bashrc file to be used from any console. It can be used with zipdiff a.zip b.zip. Piping the output to less or redirecting to a file is helpful for large zip files.

unzip -l will list the contents of a zip file. You can then pass that to diff in the normal manner as mentioned here: https://askubuntu.com/questions/229447/how-do-i-diff-the-output-of-two-commands

So for example if you had two zip files:

foo.zip
bar.zip

You could run diff -y <(unzip -l foo.zip) <(unzip -l bar.zip) to do a side-by-side diff of the contents of the two files.

Hope that helps!

If you want to diff two files (as in see the difference) you have to extract them - even if only to memory!

In order to see the diff of two files in two zips you can do something like this (no error checking or whatsoever):

# define a little bash function
function zipdiff () { diff -u <(unzip -p $1 $2) <(unzip -p $3 $4); }

# test it: create a.zip and b.zip, each with a different file.txt
echo hello >file.txt; zip a.zip file.txt
echo world >file.txt; zip b.zip file.txt

zipdiff a.zip file.txt b.zip file.txt
--- /dev/fd/63  2016-02-23 18:18:09.000000000 +0100
+++ /dev/fd/62  2016-02-23 18:18:09.000000000 +0100
@@ -1 +1 @@
-hello
+world

Note: unzip -p extracts files to pipe (stdout).

If you only want to know if the files are different you can inspect their checksums using

unzip -v -l zipfile [file_to_inspect]

Note: -v means verbose and -llist contents)

unzip -v -l a.zip 
Archive:  a.zip
 Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
--------  ------  ------- ---- ---------- ----- --------  ----
       6  Stored        6   0% 2016-02-23 18:23 363a3020  file.txt
--------          -------  ---                            -------
       6                6   0%                            1 file

unzip -v -l b.zip 
Archive:  b.zip
 Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
--------  ------  ------- ---- ---------- ----- --------  ----
       6  Stored        6   0% 2016-02-23 18:23 dd3861a8  file.txt
--------          -------  ---                            -------
       6                6   0%                            1 file 

In the example above you can see that the checksums (CRC-32) are different.

You might also be interested in this project: https://github.com/nhnb/zipdiff