They both look like very nice bikes, but neither looks like a good bike
for commuting.
The Orbea looks like it'd be very fast and light, but the frame has a very aggressive geometry (in other words, it's designed to be ridden with your back almost horizontal) and it lacks the necessary attachment points for a rack & fenders.
The Specialized is a cross-country mountain bike, with a front suspension that's great for a bumpy dirt trail, but is unnecessary and somewhat inefficient on pavement. Also, even when looking at a close up of it on
Specialized's website, I'm not 100% sure it's got the attachment points for a rack & fenders. Also note that mountain bikes use wider tires -- which is okay; I commute on a much older Specialized mountain bike and it's fine -- but they'll be a little bit slower than a bike with road-type wheels. And if the bike comes with knobby tires, then you absolutely would want to swap those out for slicks (so factor that into the cost).
Of the two, the Specialized is a better choice. However, I think you should keep looking. Look for bikes that are labeled as "touring," "hybrid" or "city" bikes. (But stay away from "cruiser" or "fixie" bikes unless your commute route is totally flat.)
By the way, a bike appropriate for an 8-mile commute doesn't have to be so fancy that it costs $300+ used. If you have access to a
bicycle co-op then you should feel free to consider even 30-year-old bikes (as long as they're in good condition).
Here are some other listings that look like they might be better choices (assuming the bike in question is the right size for you and whatnot):
http://orangecounty.craigslist.org/bik/5281587854.html (I can't tell if this has rack attachments)
http://orangecounty.craigslist.org/bik/5281510448.html (Schwinn is a cheap brand these days, but this bike already has most of the accessories you need and is a good price)
http://orangecounty.craigslist.org/bik/5281647245.html (not a great pic, but might be the best bike in this list for your needs)
http://orangecounty.craigslist.org/bik/5281634769.html (still has a front suspension, but at least it's only $100 instead of $300)
http://orangecounty.craigslist.org/bik/5276876833.html (could be good or bad depending on the condition of the Sturmey Archer internal gear hub)