<human>:  What is the difference between a sugar cookie and a shortbread cookie?
<bot>: The main difference between a sugar cookie and a shortbread cookie is the type of fat used in the dough. Sugar cookies usually use butter, while shortbread cookies use a higher ratio of fat, such as shortening, and often incorporate more sugar. Shortbread cookies typically have more of a crumbly texture and richer taste than sugar cookies.