One key difference, that you can see in the photo, is that the BV uses buckles instead of Velcro on the straps that attach the bag to the underside of the saddle, something much more important than it may seem. A pair of bike shorts (or any shorts) will shred quickly if they’re rubbing against that tiny bit of Velcro protruding from the side of the bag, and it’s sure to destroy expensive sweaters and gym clothes if you stuff the bag into your backpack or messenger bag.
Brakes come in a variety of designs depending on the age and style of your bike. Rim brakes offer more modulation but have less stopping power, so are more suited to riding on the roads. Disc brakes can provide huge amounts of stopping power so are best suited to off road riding, although ‘V’ rim brakes are also well suited to mountain biking. All brakes use a friction system to stop the movement of the wheel, so regular checks of the contact pads should form part of your regular cycle maintenance.