Difference between 'username'@localhost vs. 'username'@'%'

[nkamp01]

Hello,

What is the difference between:
CREATE USER 'username'@localhost IDENTIFIED BY '<password>';
CREATE USER 'username'@'%' IDENTIFIED BY '<password>';

[Altrea]

username@localhost can connect only from the machine the MariaDB Daemon is running on (for example by a php script if php is running on the same machine as MariaDB)
username@% can access from any host.