The WebKit on iOS is rather different from all other WebKit ports in various ways (e.g. there are various -webkit CSS properties that are only supported by WebKit on iOS and not WebKit anywhere else). And of course there are lots of Chrome features.

So the renders may or may not be the same, depending. And various DOM features that are part of UIWebView won't be the same (e.g. any DOM or HTML feature that Chrome has but Mobile Safari does not will be missing).