Which are WP Files / folders?

I have recently changed my website from Joomla to WP. I created my WP site in a sub folder (/wordpress) then when complete, I transferred it over to the root of www All went well and the site is up and running fine, however, I forgot to delete all the files that made up my Joomla site and so they are now mixed in with the WP files in the root of www. Wanting to clear up some server space I was going to delete all the old Joomla files until I looked in :-/

Can anyone confirm which are the WP files? Is everything stored in wp-admin, wp-content and wp-includes? If so (apart from index.php) can I assume its safe to delete anything otutside those folders?

Many thanks.