Is there any difference between Portal and Portal: Still Alive? Are they two separate games or just the same game remarketed separately?

As far as I can tell it's the same game with a little extra content, and now available via Live rather than as part of The Orange Box. I downloaded the demo and played it through, there was no difference between it and the first few levels of Portal.
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Yeah, that's what I thought. I purchased the Orange Box recently for Portal, finished it and found it very enjoyable. I was hoping "Still Alive" might have been a sequel but never saw those words exactly. Just saw "14 new levels"...

Yeah I'm pretty sure it's just Portal by itself.

Was probably my favorite part of The Orange Box.