superclusters are huge groups of galaxies, or, also, Cluster of Galaxy Clusters
most of them contains more than 100 000 galaxies
clusters are huge groups of galaxies, they are containing much less galaxies than superclusters
groups are galaxial clusters that are too small to be called normal cluster. Mostly, 50-150 galaxies in them.
Galaxies (shouldn't be confused with paragalaxies) are gravitationally bound systems of stars, stellar remnants, interstellar gas, dust, and dark matter.
stars are huge balls of heated gas, that made up a ball, because of gravity. Stars are classified by "spectral classes": O, B, A, F, G, K, M. There is also secondary classes: L, T, Y, C, S and D.