Key and Kaffir are two types of limes. The Key lime, also known as the Mexican lime or West Indian lime, is a small, round citrus fruit with a thin, yellow-green skin and a highly acidic flavor. It is named after the Florida Keys, where it was historically cultivated. Key limes are commonly used in desserts, such as Key lime pie, and as a flavoring in various dishes and beverages.
Kaffir lime, also known as Makrut lime, is a citrus fruit native to Southeast Asia. It is smaller and more wrinkled than a regular lime, with a bumpy, dark green skin. The distinctive feature of the Kaffir lime is its highly aromatic leaves, which are commonly used in Thai, Indonesian, and other Southeast Asian cuisines to add a unique citrusy flavor to dishes such as curries, soups, and salads. The juice and zest of the Kaffir lime are also utilized in some recipes.