Daz Studio is one program. Genesis is the default figure which comes with Daz Studio.
Bryce is a standalone prgram, basically marketed as a landscaping program, although t does far more than that.
Hexagon is a modelling program
Carrara is another program sold by Daz3D, which includes quite a few of the features that you find in the first 3 named programs.
Daz Studio 4.5, Bryce 7pro and Hexagon together make a Suite of programs which work together as there is a bridge which works from DS to Bryce, so you can export the figures and props, which you have set up in DS, to Bryce to render them in a Bryce environement. THere is also a bridge from Hexagon to DS, so you can nmodel things in Hex and send them to DS via the bridge.