What is the difference between Spearmint and Peppermint?

Spearmint (Mintha Spicata)

Is a native plant. It contains less than 1% of menthol naturally. Has subtle, gentle, sweet minty taste.

It is used in toothpastes, mosquito repellents, cosmetics.

Medicinal use is based on it's anti-inflammatory properties. Due to its anti-oxidants the tea with Spearmint may help to reduce inflammation in the body especially in Gastrointestinal tract and stomach (please consult with your doctor before use it).  May help with hiccups.

In culinary it surprisingly pairs with meat, salads. 

Peppermint (Mintha x Piperita)

Is hybrid: cross of Spearmint and Watermint. It contains 40% of menthol, which gives it cool, strong minty taste.

Medicinal use is based on it's calming, relaxing properties due to hight menthol content.  It is used in rubs to relieve body aches, headaches. Tea with peppermint relieves stress, relaxes muscles, helps with soar throat, insomnia.

In culinary it pairs with chocolate, beverages. Used in chewing gum production for breath refreshment. Most renown use of Peppermint is to make relaxing teas.