Here's the breakdown:

* Binary star systems: These are the most common type of multiple star system, containing two stars orbiting each other.

* Ternary star systems: These systems have three stars.

* Quadruple, quintuple, sextuple, etc.: Systems can have even more stars, though these become rarer as the number of stars increases.

So, while three-star systems (ternary) are a type of star system, a star system can have two, three, four, or more stars.