Voice Search is Voice Search. Google Now is just the predictive notifications and the cards (the notifications being the more signifiant part). The two are separate.
Voice Search has been available since Froyo, IIRC -- although in the past it would simply show search results rather than respond with a voice for anything other than a small set of phrases. Voice responses for more general Knowledge Graph queries is new in Jellybean. (Long-press the search button on an older phone, like a Nexus One, to trigger it.)
Voice Search has been available since Froyo, IIRC -- although in the past it would simply show search results rather than respond with a voice for anything other than a small set of phrases. Voice responses for more general Knowledge Graph queries is new in Jellybean. (Long-press the search button on an older phone, like a Nexus One, to trigger it.)