Let I've two domain names named world wide web.abc.example and world wide web.abc.example located in different servers.

I've got a .htaccess file within the root directory of world wide web.abc.example (i.e. world wide web.abc.example/.htaccess)

What would be the .htaccess script if I wish to load the items in world wide web.abc.example after i request from world wide web.abc.example.

For example: Basically browse world wide web.abc.example/test it displays this content of world wide web.abc.example/test and so forth without altering the host url (i.e. world wide web.abc.example) in browser's addressbar.

What you are attempting to do operates a reverse proxy. It takes mod_proxy around the server.

The documentation seems to suggest you will want something similar to:

ProxyRequests Off

<Proxy *>
Order deny,allow
Allow from all
</Proxy>

ProxyPass / http://www.xyz.example/
ProxyPassReverse / http://www.xyz.example/

Presuming that such configuration is permitted in .htaccess. Otherwise, you'll have to use mod_rewrite along with a RewriteRule using the [P] flag:

RewriteRule ^/(.*) http://www.xyz.example/$1 [P]

If you are going the RewriteRule route, be sure to add RewriteEngine On whether it is not there already!