Issue
I've been going through running PHP 5.6 and now looking at 7 running on CentOS 7 (typically 5.4) and I had been installing php56u and now I've been seeing php56w and I can't find anywhere what the difference is.
Solution
The last letter represents some sort of informal way of designating the origin of a third party release of PHP:
php56u = IUS Repository
php56w = Webtatic Repository
Both third party repositories compiled the source tarballs of PHP 5.6 and publicly released the package, appending a letter to its name in order to differentiate it from the official CentOS' one.
This practice doesn't represent a golden standard and every third party repository can use a different convention for releasing packages. The same PHP version released by Software Collections, for example, is named rh-php56.
Answered By - Tommaso Belluzzo Answer Checked By - David Goodson (WPSolving Volunteer)