weblogic difference between web.xml and weblogic.xml

these both files are  deployment descriptors for web applications and they exists in WEB-INF
these files define run-time environment, mapping of URL to servelets and JSPs, applications default welcome and error pages, setting up context root for the application, Specifying Java EE security constraints and defining work managers for applications


web.xml

it have following:
Servelets registration and initililization parameters.
JSP registration and tag libraries.
Welcome file lists and error pages.
Security constraints and roles.
EJB references.
Resources.


weblogic.xml
This file have information specific to weblogic.

Application root context path.
Security role mappings.
Session settings and Clustring.
References to shared libraries and server resources(data sources,EJBs and others).
Virtual directories, work managers and threading.
JSP compiler option.