The newer DAZ installers have both Poser and DAZStudio files integrated into one, hence the selection for either flavors.  I just double-checked M4's product page and indeed it appears that 1 installer contains Poser/DS files.  The PowerLoader is Studio specific and the third supplies the material files necessary for Studio.  When you install M4, you will come across a window that will specify which file types to choose.  There is a pull down menu for the selection field, select Poser (All files).  After clicking next, you will be prompted to select a runtime destination.  Hope this helps.