Tekkit Noob Question.

Hi. I have only just brought Minecraft but am really interested in playing this Multiplayer. However, I do have an issue. I have downloaded the latest Tekkit (3.1).. That works great, no problems. I do love that everything is built in for you, the high texture upgrade mod too. Now I have found some servers that I wish to join but when I try to join them I get a list of mods that need to be installed. Tekkit has these mods already installed so what is going on? then I came to the thought that maybe servers are running a lower version of these mods and even though the version of Tekkit that I am running is a higher version with possibly higher version of these mods it will not have it. So the question is. When you join a server, does it have to be the exact version of everything, server, mods etc????