Westerners generally refer to rice wine ordered in a Japanese restaurant as sake. But actually sake refers to all kinds of alcoholic beverages including nihonshu, plum wine and whisky.

Nihonshu refers specifically to brewed rice wine (not distilled). The alcohol content can vary from 12 – 20%.

Sources:

https://www.supersake.com.au/blogs/news/sake-nihonshu-the-difference

https://www.japan-guide.com/forum/quereadisplay.html?0+156346