Some background:
The format for a full URL is:
protocol://hostname[:port]URI[?parameter=value]
Port and parameter/value are optional. When someone makes a request to http://citrixvipname the browser appends a / to the end of the URL. So / is the default URI.
So with that in mind, option 1 says that if a request is made to /, redirect it to the same host that was used in the request, but with a URI of /citrix/metaframe/. If the requested URI is not equal to /, then send the request to the pool.
The second rule says that if the request starts with /citrix/metaframe/ send it to the pool. Else, if it doesn't start with /citrix/metaframe/ already, redirect the client to that URI using the same host that the request was made to.
Aaron