Gellan gum and agar are both gelling agents commonly used in the food industry. However, there are some differences between them.

Agar is derived from red algae and has been used as a gelling agent for over a century. It is heat-resistant, meaning that it can be melted and re-set, making it ideal for use in dishes that require boiling, such as jellies and custards. Agar is also widely available and relatively inexpensive.

Gellan gum, on the other hand, is a synthetic gelling agent produced through bacterial fermentation. It was developed more recently than agar, and is known for its unique gelling properties. Gellan gum is able to form gels at lower temperatures and with a wider range of pH values than agar, making it useful in applications where temperature stability and pH control are important, such as in the manufacture of low-fat and gluten-free products. Additionally, gellan gum gels are often clearer and more flexible than agar gels.

In conclusion, the choice between gellan gum and agar will depend on the specific requirements of a particular recipe or application, including the desired gel properties, cost, and availability.