There are two folders, /deploy and /patches under the /lucee-server/ folder which can be used to drop in updates to Lucee.
The /patches folder where Lucee's core jars go (.lco). When Lucee starts, it determines which jar in that folder is the latest version and it classloads that one.
The /deploy folder is a folder watched every 60 seconds by Lucee's Controller thread. It looks for (.lex) file and (.lco) files.
If Lucee find an extension (.lex), it installs it (copying it to the installed folder, among other things).
If it find a (.lco) jar, it copies it to the patches folder and forces the engine to reload the core classes immediately.
Deploy is checked every 60 seconds, patches is only checked at startup.
And the deploy folder is really just a shortcut to get the (.lco) into the patches folder of a running Lucee server without needing to restart it.
Extensions (.lex) can also be dropped in the /lucee-server/context/extensions/available folder and they can be installed using environment or jvm arguments without Lucee reaching out to the update provider.