During live TV performances do singers use voice enhancements like "auto-tunes" to help them sound good? Details inside------------>?

I found this video of Miley Cyrus singing on the Today Show. She’s awful. And, it really looks like she’s singing. Then I found this video of the exact same performance but in this one she’s actually not terrible. How do they do this? Was the first one faked, or was there another microphone that picked up her real voice and in the second one her voice was run through something like auto-tunes? I’m really curious. Any audio geeks out there care to help?