Final answer:
A binary star system consists of two stars. A star system of a few thousand stars is known as a globular cluster. A galaxy contains more than a million stars.
Step-by-step explanation:
A binary star system is made of two stars. A globular cluster is a star system that is made of no more than a few thousand stars. A galaxy is a star system that is made of more than a million stars. In the context of astronomy, 'star system' refers to a group of stars which are bound together by gravity.
Learn more about Star Systems