WebApp Sec: XSS or HTTP Response Splitting?

[Joxean Koret <joxeankoret () yahoo es>]

Hi!  
  
I have been discovered recently various security  
issues with the ViewCVS python CGI  
(http://www.securityfocus.com/archive/1/385885 )  
but I'm not sure if the errors are Cross Site  
Scripting Vulnerabilities and/or HTTP Response  
Splitting.  
  
My question is the following: What is the main 
difference  
between XSS and HTTP Response  
Splitting? May be that HTTP Response  
Splitting errors modifies the headers and XSS 
modifies document content?  
  
Thanks in advance to all... And Happy New Year!