I think both is cached. Because if the instruction list does not change, then the output of the renderer will also normally be the same. Put something like this in a syntax plugin's render() function:
$renderer->doc .= 'Now:'.time();
This outputs a timestamp which changes continuously. Each time you update your browser (e.g. F5 in Firefox) the timestamp should change. But it does not! Because the renderer output is cached to. As soon as you put ~~NOCACHE~~ into the wiki page, you will see the timestamp change with every page update.
Because the renderer output is cached too, plugins which generate dynamic content (e.g. filelist, cloud) usually disable the cache or give at least a config option which allows disabling of the cache.