These three get mixed up constantly, including on menus. Here is the difference in one page.
Soju — Korean, distilled
Clear, lightly sweet, 16–20% ABV. Distilled, then diluted. Drunk neat in small glasses with food. Made from rice, wheat, barley, sweet potato or tapioca depending on the producer.
Sake — Japanese, brewed
Sake is not a spirit at all. It is brewed from rice, like beer is brewed from barley, and it lands around 14–16% ABV. It carries more body, more aroma and more rice character than soju, and it is served in a wider range of temperatures.
Shochu — Japanese, distilled
Shochu is the closest relative to soju: a Japanese distilled spirit, usually 20–25% ABV, made from barley, sweet potato, rice or buckwheat. Unlike most mass-market soju, shochu is typically unsweetened and tastes strongly of whatever it was made from — sweet-potato shochu is unmistakable.
The one-line test
- Brewed, delicate, rice-forward → sake
- Distilled, clean, faintly sweet, small green bottle → soju
- Distilled, dry, tastes of its base ingredient → shochu
Why the confusion exists in California
For years, licensing rules led some Japanese shochu in California to be sold under the word “soju” so that beer-and-wine venues could pour it. If you have ever ordered soju and been handed something that tasted like sweet potato, that is why.