Simple question. What's the distinction between %1 and $1 inshtaccess?

For instance,

    #  to remove www  
    RewriteCond %{HTTP_HOST} ^(\w+)\.mydomain\.com [NC]

    RewriteRule .* http://mydomain.com/%1 [R=301,L]    
    #    versus
    #    RewriteRule .* http://mydomain.com/$1 [R=301,L]

I've been using Dave Child's .htaccess cheat sheet and Jackol's .htaccess cheat sheet along with the Apache mod_rewrite docs but additional help could be great.

%1 Describes a pattern matched up inside a RewriteCond condition, while $1 describes a pattern matched up in the RewriteRule.

More generically, use %n to consult the designated matches from RewriteCond condition regex designs, and employ $n to consult designated matches from RewriteRule regex designs.