Both models are just fine. If either one of them has a detachable hose that's a nice feature to have. But not worth a big price difference.
If you already have a backpack with which you bike you can just throw it in there. Get the hose out and tie it to one of the shoulder straps.
If you don't have one there are at least two options for buying a backpack.
One is a backpack with a special camelback pocket and a nice hole through which to take out the hose. I use this one. Note the inside water bag pocket.
The other one is to have a dedicated, very light, camelback-only backpack. I don't really have a use for those but I've seen a lot of people using them. I prefer the extra features of a day-hike backpack.
My favorite water bag is the one from Source. It never leaked and I have it for years now. Very robust.
Stay away from Ferrini models. They leak and are very volatile!