App types: creating views or bar charts

Hi, this is a silly-rookie question:

I noticed that some database Apps have “empty” icons and some Apps have icons filled with lines.
When I add a new App, I get only Apps with an icon without lines. What is the difference between the two? Can I somehow transform one into the other?

I noticed that in Apps with “empty” icons I cannot create views or bar charts for categories (i.e. #records per country).

So I guess this is most likely some basic database issue which I should know - but unfortunately I don’t.
Where would I find information on this? How do I create an App where I can create views by specific categories (not only date) or respective bar charts in a dashboard?

Thanks so much,
Konny