Not really quite sure what you mean or at what level you are talking but you could talk about Galaxy types and structure.
Spiral, barred spiral, eliptical galaxies. Globular clusters that orbit galaxies and contain the oldest stars.
And then the wider structures. Our local group of Galaxies made up of our own milky way, Andromeda and the Magellenic cloud all the way up to galactic superclusters
http://en.wikipedia.org/wiki/Supercluster