I view "compfort bikes' as a type of hybrid -- meaning that they are a subset of the group. Comfort bikes usually have an extremely upright sitting position and big pillowy saddle... And, clearly, they are built for one thing: comfort.

Conversely a regular hybrid, as you know, tends to do all things pretty well. It can go on the road or off. I would not want to take a comfort bike on anything but a smooth trail for any extended period of time. I think the most notable part of the comfort bike is its upright position. And, for myself, I would only go that route if I couldn't get down over the bars a little.

As for where to buy: one advantage of WalMart over Bikes Direct is that you can at sit on the bike before you buy it.

I think every experienced cyclist will agree that the single most important feature of any bike is how well it fits you. And, at least in the higher end bikes, every model comes in a variety of sizes: 15", 17.5" 19", 22", etc... First you want to be looking at the right size for your body. But, even within that size, there are significant differences in fit amongst the various models -- and you can't discern that by reading a description. You can only discern the differences by riding on them -- the longer and further the better.

A good local bike shop (LBS) will be able to steer you in the right direction and most have lower end bikes that, while not in the WalMart range, may still be affordable. And, while not all LBS's are good LBS's, the good ones will take the time to match the model and the size you and your needs -- and then work with you find the one that is just right for you -- and THEN get it setup they you need it or prefer it.

So, my order of shopping for a first bike would be: LBS, BigBoxStore, Online

Most people recommend the LBS route because not only do you get a bike that fits, but it will be of high enough quality that you won't get discouraged and disgusted with it.

ps. Some hybrids are closer to mountain bikes and some are closer to road bikes. For instance, the Trek FX line are essentially road oriented but they can go on a smooth trail. Or, the Trek DS line can go on a rough trail but can also deal with roads to a certain extent. The differences however are kind of subtle. But, I would not go with a mountain bike unless you intended to ride it on rough trails, through woods, and so on. I find them too heavy and too slow on smooth bike paths.