rsp is an pc which has remote access of some sort, these are mostly dedicated servers shared among various users for file uploading purposes etc, they are mostly like your own pc without some features like higher graphics etc
vps are mostly built on virtual technology like vmware etc in which each user is given a specific amount of system resources, they are mostly used for web hosting and in some cases as rdp's
RL is short for rapidleech and it a script that leeches from popular hosts and rar's unrars them and uploads them for you, you control its options via a web interface

thats what i know if anyone else wants to add he can