The question has to be more generic like Differences between Skinnablecontainers and Group
Explanation:
The border container
extends SkinnableContainer, so skinClass can be applied to the skinnable container, So, along with children, we can skin the way the container looks by using these containers. These are a little heavy weight components as it has to draw skin every time the user tries to do invalidation on the component.
Groups
are light weight containers. these are used only to layout children, you will not be given tools to apply skin on it as they are used only to display children(children can have their own skin).
More on it here