They share a common platform, the top section is what separates them.
The Razor or older Cobra series stands are actually better suited for bowhunting due to the open or potential for an open front but require significantly more effort to climb with.

The Viper and Goliath are however excellent bowhunting stands provided you learn the proper way to set seat and bar height.
If you aren't a wide body the Viper is plenty and will allow easier shooting over and around the bar, and either are a breeze to climb with and as secure as they come in the tree.

WATCH THE DVD that comes with the stand if you get one.