Topaz Labs_ is where you will find their original filter plugins to use in a host editor... like Photoshop etc. (And also from within Studio).
Topaz Studio_ is where you can download Topaz Studio which is a Free standalone editor with 10 free adjustments. You do not have to have Photoshop to use their image editing adjustments. There are other Pro adjustments to try with a trial and purchase after 30 days. And if you already own any of their previous Plugins you can access them from within the Studio menu as well.... and if you do use something like Photoshop etc.. you can access Studio from within that program.