Is it possible to copy the Users file/table from one website to another?

You can simply Export the tables  from PHPMyAdmin (from cpanel / plesk / directadmin) on your hosting provider panel.
There is an advanced form you can select the format csv or Mysql and other settings like selecting only the table / data you need.

In the case of a CMS like Joomla, you can't really use phpMyAdmin to do an export.

Because...

On import, the CMS based code will handle things like user id + name + email addresses (etc) collisions + ask you how to resolve each.

Doing a brute force import of CMS user data from a phpMyAdmin generated export will...

1) Completely  crash your site if your lucky.

2) If your unlucky your site data will be so corrupted your site may continue running... then either crash in the future or end up with out of sync data.

For CMS systems, best to use normal export + import code provided by smart people who've built in collision resolution logic.

@David I worked with Joomla since the start (remember Mambo prior 2005) , I never add any issue exporting and importing the users.

The only thing is if you use a component like community builder you need to also export these table in order to get all the info.

I'm making an excel sheet and bind all the information and if I need to put these new user inside another datatabase that have already user ID I do adjust the ID prior the import. But if the other DB is a new empty DB you won't have any problems has there is no existing ID.

Thanks, David.  Very Useful.