no they are not unrelated.
I reported in one of the world ID mismatch threads that I was having the problem discussed here, later I reported in the thread I made about the forge essentials that I had finally gotten my server to launch, generate a world, and allow me to log in, which means that my fix also addressed the world ID mismatch that is being discussed here.
What I don't know is if anyone else can get the same results, which is why i'm asking ppl who have had this issue if following my instructions fixes it for them.
(then i had to assign the forge essentials permissions as sticky-ed at the top of the tekkit lite board before i could open any chests :S)
can anyone who has had this problem can tell me if this works for them too? http://forums.technicpack.net/threads/forge-mod-loader-server-error-fix.35541/
issue was previously reported in this thread http://forums.technicpack.net/threads/id-mismatch-between-server-and-client.35033/
(it had been bumped back to page 2 when this thread was created)
same here, using windows 7 64bit for the client machine, the server is a Linux host, re-installed the launcher twice, upgraded to java 7 twice (first time i let it auto update, then i made sure to get the the 64bit version specifically) reset the server files twice, nothing fixes it, and editing the railcraft.cfg file doesnt help