Hi Liz, Stearic Acid will set all the ingredients, making the final product to look like a gel. Also it is used in soap industry (depending on how much it is used will set the product).Stearic acid is made by treating animal fat with water at a high temperature and pressure. It can also be obtained from the hydrogenation of some unsaturated vegetable oils, usually coconut oil. And the third type is just just chemical. Also the term 'stearic' is derived from the Greek word 'stéar', which means 'tallow'. So if you want a 100% natural stearic acid look for the vegetable oils based one.
On the other hand citric acid is a natural preservative, offering to the beauty product a longer shelf life. Hope it helps, Cheers-Kate