Here are some other terms that might be helpful:

* Constellation: A group of stars that form a recognizable pattern in the night sky.

* Star cluster: A group of stars that are gravitationally bound together. There are two types:

* Open clusters: Loosely bound groups of stars that are often young and hot.

* Globular clusters: Tightly bound groups of stars that are very old and dense.

So, while all of these terms relate to groups of stars, "galaxy" is the term for the largest and most expansive grouping of stars.