ServletContext is created only once in a whole application 
whereas servletConfig is created for each servlet in an 
application.

In ServletContext value will b same for whole application
and were as the servletConfige value will b seprate or
diffrant for all the application in the project..

Every  web application has only one SContext object.
There are n number of SConfig objects in an Web app where
n is the number of servlets. It is specific to a servelt.  
ServletContext is used to get the context parameters.
ServletConfig is used to get to the init parameters.

ServletContext: One Object(ServletContext) for application
ServeltConfig: It is specifig to a servelt in an 
application. Each servlet will have a ServletConfig

servletcontext:
1) servletcontext object one for webapplication
2)it used global init parameters
3)with help servletcontext object we find our webserver
ingformation(public java.lang.String 	getServerInfo())

servletConfig:

1)servletConfig object will be created every servlet suppose
in my webapplication 10 servlets are their 10 servletConfig
object will be created but only one SwervletContext object
will be created
2) it is the righthand object of servlet
3)it used local init parameters
4)with help of servletConfig object we find out logical name
of servlet(public java.lang.String getServletName())