One is price. It won't hold hooks well enough to work on, and it won't be enjoyable to tie on. So don't waste your money. In the same vein, you do NOT have to spend a fortune, or take out a second mortgage to get a wonderful tool on which to tie flies. A variable to consider here is the jaws.
Some vises use one set of jaws for all sizes of hooks - very convenient.
True rotary vises use offset jaws. If you work with epoxy at all, make sure your vise has 360 degree rotational jaws. If not you'll have an unholy mess on your hands, and your lap, your tying table, everywhere. Which to buy is really a matter of personal taste. In my opinion both work equally well.