The difference between components and non-components is hardly visible and only is due to the fact that with non-components you have additional tabs based on categories (lines, pads, arcs, surfaces, texts) to help you find the object you are looking for more easily. To invoke the Attribute Histogram dialog you have to right click on the concerning layer in the layer panel and select "Show Attribute Histogram" to get a list of all component attributes and their respective values.

If you have more than one layer activated for visualisation and you use the mouse gesture to get to the Attribute Histogram dialog, it will always show you the data for the most activated layer of your layer stack up.