Hi amatsukaze.
The smooth tool is a so-called active tool. It indeed does basically the same as the ‘old’ W > Smooth Vertices, it just acts a bit different, like you said.
You have now two ways of smoothing:
use the smooth tool, or
use the ‘old’ context menu.
When you are using the now default ‘Left Click Select’, you can right click anywhere in the viewport and get the context menu.
If you are using ‘Right Click Select’ you can access the context menu by pressing W, like in the old days.