Emin, My personal view is that you would not want to use the same tool for carpets and upholstery.
I use Prochem tools and have stair tool and S/S upholstery tool. You do NOT want to overwet upholstery so by using uph tool, you only spray a mist. (You can go over areas more than once without soaking)
I also feel that stair tools can get scratched/gouged on grippers so not good to use on upholstery in case of tears etc.
Welcome to the world of Carpet Cleaning and the forums
Lets be careful out there people.