What is the difference between wait_timeout and interactive_timeout?

interactive_time is for interactive sessions, whereas wait_timeout is for non-interactive sessions.

What's an interactive session? It's one with a human at the keyboard.

When your code connects to MySQL, runs a query and then spends 3 seconds processing that query before disconnecting, that's 3 seconds of the wait_timeout.

When you use the mysql command line client to connect, run a command and spend 10 seconds reading the output, that's 10 seconds of interactive_timeout. If you walk away and have lunch, that's 3600 seconds of interactive_timeout.

In both cases, when you or your code runs another query, the waiting time is reset back to 0.

You can see the values for all the current sessions by typing show processlist. The values in the sleep(5) function is the number of seconds since that connection last did anything.