S-Voice is Samsung's Bizarro-like clone of Apple's Siri voice assistant service, and like any Bizarro worth its chalky skin, it seems to be hugely conflicted about it's progenitor. Alex Dobie of Android Central reports:
On the international Samsung Galaxy S4 (and some other Samsung phones -- we've had varying results), asking S Voice if it's ever used an iPhone prompts the response "No, I have standards." Ask it "Are you Siri?" and it's a little more coy -- "I like to think I am."
In my tests, Siri has no opinion on, or frankly any idea what a "Galaxy S" or an "S Voice" was, but helpfully offered to perform a web search if I really wanted to find out. Serious question, though: Any advantage to using S Voice over Google's phenomenal Voice Search and Google Now features anyway?
Source: Android Central