LAMP is an acronym for Linux, Apache, MySQL, and PHP. Some fudging goes on from some people who use other software (I've seen "Linux, Apache, Middleware, PostgreSQL", and even "P" standing for "Perl").
A GUI desktop interface is generally overkill for a server, which therefore doesn't usually have one installed; it's more likely to be accessed via a remote shell (because connecting via the network is easier than physically hauling a keyboard and monitor over and plugging them into the server).