Sochu is a distilled beverage with less than 45% alcohol by volume. It is made from rice and a group of vegetables.
Shōchū is typically distilled from rice, barley, sweet potato, buckwheat, or brown sugar. Sochu is sometimes produced from other ingredients like chestnuts, sesame seeds, potatoes or even carrots.
Shōchū contains 25% alcohol by volume which is weaker than whisky or standard-strength vodka, and stronger than wine and sake. It is not uncommon for multiple-distilled shōchū to be used in mixed drinks (up to 35% alcohol by volume).
Shōchū originated in Kyūshū but is produced in various locations throughout Japan.
Don’t confuse shōchū with sake. Sake is brewed rice wine.
Shōchū is drunk in many ways according to season or personal taste. It can be drunk neat. You can have it “on the rocks”. It can be diluted with room temperature or hot water, mixed with oolong tea or fruit juice as chūhai, a mixed drink consisting of shōchū, soda, ice and some flavoring. Often lemon, grapefruit, apple or ume (sour fruit) or mixed with a low-alcohol beer-flavoured beverage known as hoppy.
Shōchū is widely available in supermarkets, liquor stores and convenience stores in Japan while canned chuhai drinks are sold in some vending machines.
From my experience – it is recommended that you take to sochu with caution! It is not really my kind of drink, but Monsieur Contrôleur has a different perspective.