The frames are going to be similar in quality. They might even come from the same huge factory in Taiwan or China.
As far as component quality goes, they're about the same. Nothing rules at this price point, but nothing really sucks, either. They're better than just about anything you'll find on the racks at Wal-Mart. The Trek's using an Alivio mountain bike rear derailleur because its rear cassette is what you'd find on a mountain bike; the Vita's Sora rear derailleur matches its road bike-style cassette. They're fairly equivalent in quality.
The Trek has a lower low gear and faster top gear, but both bikes are nearly capable of pulling tree stumps in their bottom gear. I might actually prefer the Vita's closer ratios in the rear cassette. You'll have to be going above 30 mph on either bike before you can't pedal fast enough.
The Vita's suspension seatpost has preload adjustment, which means that you'll be able to adjust how stiff it is. A friend of mine has a Specialized Dolce with a seatpost that can be locked fully rigid (not sure whether it's a Specialized post or not), which is nice when the road is smooth and you want better pedaling efficiency. A lot of people here will never use a suspension seatpost, but still, I've got a bike with a cheap suspension post, and I like how plush it rides.
The Trek's got Clix dropouts, which look neat but, to me, seems kinda unnecessary. Info here:
Pedals are pedals; none of my bikes have their original pedals anymore.
Between those bikes, I'd go with the Vita. Don't be surprised if you develop a hankering for a road bike after a couple thousand miles (or sooner
). If you do, and you get a second, faster bike, I think the Vita will do better than the Trek as an easygoing, comfortable bike.