You may set style and other parameters in module but also you may create one profile in back-end and use it, in many modules and/or components or even with plugin.
When you place Category Block into a module you have a fixed-size block which may have Scroll Bars (Horizontal, Vertical or Both) or it may float slowly from bottom to top like a news line, but vertical.
On this page you may see both examples, one with a scroll bar on top (with red border) and another with "Auto Flow" with green border.
You may adjast a lot of settings, see screen-shot below:
Or use profile:
One more example of Category Block usage: