nop its a big GO
the databases are the same the envir is 95% the same only diffrent is that u have in 3.55 a handfull more scripts but that can translate self by altavista bablefish(search for in google

) so u set up ur 3.38 server if all is running u take ur folders from 3.38 in the 3.55 serverfiles and put it to the same place (foldername) the 3.38 had before and all should work fine
only diffrent if u prefer the large old maps u must use another client as for the new files (smaller maps)
if u prefer the bigmaps than feel free to take the client from reddragon server if u have none 3.55.
(my client is for 3.38 so u can only use for 3.38 to connect but u can grab items and so on) a client with new maps is for example zentaurclient for 3.55