How to compare two env variable

Urgent help

[DeveloperMind]

Can we compare two variable like following

SetEnvIfNoCase Host ([a-zA-Z]{2,3})\.([a-zA-Z]+).* HostName=$2
SetEnvIfNoCase Referer [([a-zA-Z]{2,3})\.([a-zA-Z]+).*...] RefererName=$2

RewriteCond %{HTTP_HOST}!([[:print:]])%{ENV:RefererName}([[:print:]])
RewriteRule (.*) [www\.google\.com...] [R,L]

Thanks in advance
DeveloperMind