noun
Specifically refers to our own galaxy, the Milky Way. In astronomy contexts, it is the proper name.
夏の夜空には銀河がくっきりと見える。
In the summer night sky, the Milky Way is clearly visible.
noun
General term for any galaxy, including the Milky Way. Often used in compounds like 銀河系 (galactic system) or 銀河団 (galaxy cluster).
この銀河は地球から約250万光年離れている。
This galaxy is about 2.5 million light-years away from Earth.